[m-rev.] diff: update README.MacOS

[Julien Fischer]

Update README.MacOS:

README.MacOS:
     Rename to README.macOS.md.

     Fix markdown in a few spots.

     Add a missing word.

     Describe the OS as "macOS", which is what Apple currently call it.

     Fix up some links.

README.md:
     Conform to the above change.

Julien.

diff --git a/README.macOS.md b/README.macOS.md
index 4744f8b25..3bddf361b 100644
--- a/README.macOS.md
+++ b/README.macOS.md
@@ -1,10 +1,10 @@
  Mercury on macOS
  ================

-This file documents the port of Mercury to Mac OS X / OS X / macOS,
-i.e. the `*-apple-darwin*` configuration. 
+This file documents the port of Mercury to macOS / OS X / Mac OS X
+(i.e. the `*-apple-darwin*` configuration).

-Versions of Mac OS X prior to 10.9 are not supported.
+Versions of macOS prior to 10.9 are not supported.

  Contents
  --------
@@ -12,12 +12,12 @@ Contents
  * Mercury on Intel Macs
  * Note for users of Xcode 11
  * Deployment Target Settings
-* Deep profiling on Mac OS X
+* Deep profiling on macOS

  Mercury on Intel Macs
  ----------------------

-Mercury should build and install "out-of-the-box" on Intel Macs using Mac OS X
+Mercury should build and install "out-of-the-box" on Intel Macs using macOS
  10.9 onwards.

  The `asm_fast*` and `reg*` grades are only available on 64-bit Intel systems
@@ -26,7 +26,7 @@ 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
  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 for further details.)
+(See [README.CSharp.md](README.CSharp.md) for further details.)

  If the `asm_fast.gc` grade is not available, and unless otherwise directed,
  then the `hlc.gc` grade will be used as the default grade for compiling
@@ -34,19 +34,23 @@ applications.

  On x86-64 machines, the default is to install 64-bit versions of the
  executables and libraries in the Mercury system.  On machines running versions
-of MacOS up to and including 10.14, users can choose to install 32-bit versions
+of macOS up to and including 10.14, users can choose to install 32-bit versions
  instead by invoking Mercury's `configure` script either with the option

+```
      --with-cc="clang -m32"
+```

  or

+```
      --with-cc="gcc -m32"
+```

  depending on their preferred compiler. In either case, every invocation
  of the selected C compiler on Mercury-generated C files will specify
  the `-m32` option. The reason for the limitation to 10.14 is that
-32-bit executables are not supported at all from MacOS 10.15 onwards.
+32-bit executables are not supported at all from macOS 10.15 onwards.

  If, after installing Mercury, you encounter errors about missing `.mih` files,
  and you have fink installed, then try removing the fink components from your
@@ -60,18 +64,19 @@ that *cannot* be used to compile Mercury.  The `configure` script will print
  a warning if it detects that you are using the broken version.

  A discussion of this issue can be found at
-<https://forums.developer.apple.com/thread/121887>.
-The github post
-<https://github.com/Mercury-Language/mercury/issues/88#issuecomment-624329679>
+[this](<https://forums.developer.apple.com/thread/121887>) thread in the Apple
+Developer forum.
+This
+[post](https://github.com/Mercury-Language/mercury/issues/88#issuecomment-624329679)
  describes a way that has been found to fix the problem.

  Deployment Target Settings
  --------------------------

-By default, the Mercury compiler is configured so that the Mac OS X deployment
-target for code generated by the Mercury compiler is set the value of the
-`MACOSX_DEPLOYMENT_TARGET` environment variable (if set), or else to the
-MacOS version of the host system.
+By default, the Mercury compiler is configured so that the macOS deployment
+target for code generated by the Mercury compiler is set to the value of the
+`MACOSX_DEPLOYMENT_TARGET` environment variable (if set), or else to the macOS
+version of the host system.

  You can specify a different deployment target at configuration time using
  the `configure` script's `--with-macosx-deployment-target` option.
@@ -79,12 +84,12 @@ the `configure` script's `--with-macosx-deployment-target` option.
  (See the "SDK Compatibility Guide" in the Apple developer documentation
  for further information about the deployment target setting.)

-Deep profiling on Mac OS X
---------------------------
+Deep profiling on macOS
+-----------------------

-The Mercury deep profiler requires a local web server.  To use the deep
+The Mercury deep profiler requires a local web server. To use the deep
  profiler:

-- select and install a web server, and
-- install and enable the `mdprof_cgi` script according to the rules of that
+- Select and install a web server, and
+- Install and enable the `mdprof_cgi` script according to the rules of that
    web server.
diff --git a/README.md b/README.md
index 92ffc1017..eb7d44c20 100644
--- a/README.md
+++ b/README.md
@@ -42,7 +42,7 @@ Specific information is contained in individual README files:
        * [Linux](README.Linux)
          ([PPC](README.Linux-PPC),
          [m68k](README.Linux-m68k))
-      * [MacOS X](README.MacOS)
+      * [macOS](README.macOS.md)
        * [FreeBSD](README.FreeBSD)
        * [OpenBSD](README.OpenBSD)
        * [AIX](README.AIX)