Minor clean-ups and fixes for README files.

Documentation/README*:
    As above.

Documentation/README.CSharp.md

@@ -52,12 +52,11 @@ can build programs such as `hello.m` or `calculator.m` in the [samples](samples)
 directory.
 
 ```
-    $ cd samples
-    $ mmc ---grade csharp --make hello
+    mmc --grade csharp --make hello
 ```
 
-When building programs with the `csharp` grade you *must* use `mmc --make`; using
-`mmake` to build programs using the `csharp` grade is _not_ supported.
+When building programs with the `csharp` grade you *must* use `mmc --make`.
+Using `mmake` to build programs using the `csharp` grade is _not_ supported.
 
 Running `csharp` grade programs with Mono
 -----------------------------------------
@@ -72,7 +71,7 @@ It will then invoke then CLI execution environment on the process assembly.
 You can run the program using wrapper shell script, for example:
 
 ```
-    $ ./hello
+    ./hello
 ```
 
 Running `csharp` grade programs on Windows with .NET

Documentation/README.Java.md

@@ -58,8 +58,7 @@ build programs such as `hello.m` or `calculator.m` in the [samples](samples)
 directory.
 
 ```
-    $ cd samples
-    $ mmc --grade java --make hello
+    mmc --grade java --make hello
 ```
 
 When building programs with the `java` grade you *must* use `mmc --make`; using
@@ -71,7 +70,7 @@ Running programs with the `java` grade
 You can run the `hello` program from the previous section by doing:
 
 ```
-    $ ./hello
+    ./hello
 ```
 
 Note that `hello` is a simple shell script generated by the Mercury compiler
@@ -239,7 +238,7 @@ information. You can include local variable debugging information by specifying
 `--target-debug` when invoking the Mercury compiler. For example:
 
 ```
-    $ mmc --grade java --target-debug --make <progname>
+    mmc --grade java --target-debug --make <progname>
 ```
 
 You can then use the `jdb` debugging tool, which comes as part of the Java SDK
@@ -269,15 +268,15 @@ However, if you want to give it a try, the required steps are:
 
 4. Build the dependencies using the following command:
 
-        $ mmake --use-mmc-make depend GRADE=java
+        mmake --use-mmc-make depend GRADE=java
 
 5. Compile using the following command:
 
-        $ mmake --use-mmc-make GRADE=java
+        mmake --use-mmc-make GRADE=java
 
 6. To install the Java version of the compiler, do:
 
-        $ mmake --use-mmc-make install GRADE=java
+        mmake --use-mmc-make install GRADE=java
 
 The Java version of the compiler MUST be built using `mmake`'s `--use-mmc-make`
 option; the build will not work otherwise. Setting the variable `GRADE` in the

Documentation/README.Linux-aarch64.md

@@ -9,4 +9,4 @@ Mercury should build and install "out-of-the-box" on Linux for AArch64.
 Low-level C grades using non-local gotos, i.e. `asm_fast.*`, do not work
 with GCC 9 or later. Non-PIC (position-independent code) actually does
 still work, but PIC is commonly the default.
-If you require a low-level C grade, please use a `reg.*` grade.
+If you require a low-level C grade, then please use a `reg.*` grade.

Documentation/README.MS-VisualC.md

@@ -87,7 +87,7 @@ In either case, to use MSVC as the C compiler with Mercury, invoke `configure`
 as follows:
 
 ```
-    $ ./configure --with-cc=cl [--with-msvcrt] [<any other options>]
+    ./configure --with-cc=cl [--with-msvcrt] [<any other options>]
 ```
 
 The `--with-msvcrt` flag causes executables built with this install of Mercury
@@ -101,20 +101,25 @@ with a drive letter, except that you must use `/` instead of `\` as a directory
 separator. For example, this is acceptable:
 
 ```
-    $ ./configure --prefix="c:/where/to/install/mercury"
+    ./configure --prefix="c:/where/to/install/mercury"
 ```
 
 but this is not:
 
 ```
-    $ ./configure --prefix="c:\where\to\install\mercury"
+    ./configure --prefix="c:\where\to\install\mercury"
 ```
 
 Once `configure` has successfully finished, then you should do
 
 ```
-    $ make 
-    $ make install
+    make
+```
+
+and then
+
+```
+    make install
 ```
 
 as normal.
@@ -165,7 +170,7 @@ The MSVC port currently has a number of limitations:
   and also enable the commented out definition of `CFLAGS_FOR_DEBUG` in
   `configure.ac` (in the `msvc*` case). You will then need to regenerate
   the `configure` script and rebuild the Mercury system.
-  (See [INSTALL.git](Install.git) for details of how to do this.)
+  (See [../INSTALL.git](Install.git) for details of how to do this.)
 
 Post-installation configuration
 -------------------------------
@@ -229,13 +234,13 @@ Then ensure that the directory that you wish to install into is mounted
 somewhere, i.e.
 
 ```
-    $ mount //foo/usr/local /temp_mount_point
+    mount //foo/usr/local /temp_mount_point
 ```
 
 and then use that mount point as the location to install into
 
 ```
-    $ make install INSTALL_PREFIX=/temp_mount_point
+    make install INSTALL_PREFIX=/temp_mount_point
 ```
 
 This avoids the problem that `mkdir -p //foo/usr/local/xxx` fails.

Documentation/README.clang.md

@@ -18,5 +18,5 @@ Versions of LLVM (the underlying compiler infrastructure used by `clang`) before
 about version 2.9 contain bugs that require most C compiler optimizations to be
 disabled when compiling Mercury generated C code with `clang` (i.e. the
 generated C files have to be compiled at `-O0`). If you are using a more recent
-version of LLVM then the `configure` script will automatically enable a higher
+version of LLVM, then the `configure` script will automatically enable a higher
 level of optimization.

Documentation/README.cross.md

@@ -1,5 +1,5 @@
 Cross-compiling Mercury with GCC or clang
-========================================
+=========================================
 
 You can cross-compile the Mercury system with GCC or with clang so that the
 Mercury installation will run on a different platform from your host system.

Documentation/README.macOS.md

@@ -25,7 +25,7 @@ Macs using macOS 10.9 onwards.
 The `asm_fast*` and `reg*` grades are only available on 64-bit Intel systems
 and only when using GCC version 4.3 or later as the C compiler.
 
-If `clang` is being used as the C compiler then the only low-level C grades
+If `clang` is being used as the C compiler, then the only low-level C grades
 available are the `none*` grades. The high-level C, Java and C# grades
 all work. The C# grades require the Mono .NET implementation.
 (See [README.CSharp.md](README.CSharp.md) for further details.)

Documentation/README.ssdebug.md

@@ -60,7 +60,7 @@ the environment variable `SSDB` beforehand.
     ssdb>
 ```
 
-If you set `SSDB=0` then you will need to explicitly enable the debugger later
+If you set `SSDB=0`, then you will need to explicitly enable the debugger later
 in your code by calling `ssdb.enable_debugging/2`.
 
 As in `mdb`, the three numbers are the event number, call sequence number (CSN)
@@ -95,7 +95,7 @@ Limitations
 * The `retry` command works by executing forwards until reaching the end of
   the call to retry, then recursively calling that procedure. Any side
   effects of continuing execution will be visible. If it is not possible to
-  reach the end of the procedure to retry, the program will simply keep
+  reach the end of the procedure to retry, then the program will simply keep
   executing. Press ^C to get back the debugger prompt.
 
 * When running on Mono 2.8 and earlier, ^C can cause the program to hang.