Revise some renamings of NOTES and README files

Some of the notes and readme files have been converted to markdown
format recently and renamed during this process. While adding the
.md extension was a natural step, switching to mixed cases was not
a change to the better, it gives them a ragged appearance:

     NOTES.ANDROID  => NOTES-Android.md
     NOTES.DJGPP    => NOTES-DJGPP.md
     NOTES.PERL     => NOTES-Perl.md
     NOTES.UNIX     => NOTES-Unix.md
     NOTES.VMS      => NOTES-VMS.md
     NOTES.VALGRIND => NOTES-Valgrind.md
     NOTES.WIN      => NOTES-Windows.txt
     README.ENGINE  => README-Engine.md
     README.FIPS    => README-FIPS.md

Moreover, the NOTES-Windows.txt file is the only file which has been
converted to markdown but has received a .txt file extension.
This doesn't make sense, because the OpenSSL users on Windows will
need to read the other markdown documents as well. Since they are
developers, we can trust them to be able to associate their favorite
editor with the .md extension.

In fact, having a comment at the beginning of the file saying that it
is in markdown format but we didn't dare to add the correct extension
in order not to overwhelm our Windows users can be interpreted either
as unintentionally funny or disrespectful ;-)

This commit suggests the following more consistent renaming:

     NOTES.ANDROID  => NOTES-ANDROID.md
     NOTES.DJGPP    => NOTES-DJGPP.md
     NOTES.PERL     => NOTES-PERL.md
     NOTES.UNIX     => NOTES-UNIX.md
     NOTES.VMS      => NOTES-VMS.md
     NOTES.VALGRIND => NOTES-VALGRIND.md
     NOTES.WIN      => NOTES-WINDOWS.md
     README.ENGINE  => README-ENGINES.md
     README.FIPS    => README-FIPS.md

(note the plural in README-ENGINES, anticipating a README-PROVIDERS)

Reviewed-by: Paul Dale <pauli@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/14042)

Configurations/unix-Makefile.tmpl

@@ -1041,7 +1041,7 @@ cmd-nits: build_generated apps/openssl build_generated_pods
 # Finally, there's a Node.js version, which we haven't tried, that
 # can be found at https://github.com/DavidAnson/markdownlint
 md-nits:
-	mdl -s util/markdownlint.rb . NOTES-Windows.txt
+	mdl -s util/markdownlint.rb .
 
 # Test coverage is a good idea for the future
 #coverage: $(PROGRAMS) $(TESTPROGRAMS)

INSTALL.md

@@ -48,8 +48,8 @@ Prerequisites
 To install OpenSSL, you will need:
 
  * A "make" implementation
- * Perl 5 with core modules (please read [NOTES-Perl.md](NOTES-Perl.md))
- * The Perl module `Text::Template` (please read [NOTES-PERL.md](NOTES-Perl.md))
+ * Perl 5 with core modules (please read [NOTES-PERL.md](NOTES-PERL.md))
+ * The Perl module `Text::Template` (please read [NOTES-PERL.md](NOTES-PERL.md))
  * an ANSI C compiler
  * a development environment in the form of development libraries and C
    header files
@@ -58,13 +58,13 @@ To install OpenSSL, you will need:
 For additional platform specific requirements, solutions to specific
 issues and other details, please read one of these:
 
- * [NOTES-Unix.md](NOTES-Unix.md) - notes for Unix like systems
+ * [NOTES-UNIX.md](NOTES-UNIX.md) - notes for Unix like systems
  * [NOTES-VMS.md](NOTES-VMS.md) - notes related to OpenVMS
- * [NOTES-Windows.txt](NOTES-Windows.txt) - notes related to the Windows platform
+ * [NOTES-WINDOWS.md](NOTES-WINDOWS.md) - notes related to the Windows platform
  * [NOTES-DJGPP.md](NOTES-DJGPP.md) - building for DOS with DJGPP
- * [NOTES-Android.md](NOTES-Android.md) - building for Android platforms (using NDK)
- * [NOTES-Valgrind.md](NOTES-Valgrind.md) - testing with Valgrind
- * [NOTES-Perl.m](NOTES-Perl.md) - some notes on Perl
+ * [NOTES-ANDROID.md](NOTES-ANDROID.md) - building for Android platforms (using NDK)
+ * [NOTES-VALGRIND.md](NOTES-VALGRIND.md) - testing with Valgrind
+ * [NOTES-PERL.m](NOTES-PERL.md) - some notes on Perl
 
 Notational conventions
 ======================
@@ -285,7 +285,7 @@ Configuration Options
 There are several options to `./Configure` to customize the build (note that
 for Windows, the defaults for `--prefix` and `--openssldir` depend on what
 configuration is used and what Windows implementation OpenSSL is built on.
-More notes on this in [NOTES-Windows.txt](NOTES-Windows.txt):
+For more information, see the [Notes for Windows platforms](NOTES-WINDOWS.md).
 
 API Level
 ---------

NOTES-DJGPP.md

@@ -10,7 +10,7 @@ INSTALLATION ON THE DOS PLATFORM WITH DJGPP
  You should have a full DJGPP environment installed, including the
  latest versions of DJGPP, GCC, BINUTILS, BASH, etc. This package
  requires that PERL and the PERL module `Text::Template` also be
- installed (see [NOTES-Perl.md](NOTES-Perl.md)).
+ installed (see [NOTES-PERL.md](NOTES-PERL.md)).
 
  All of these can be obtained from the usual DJGPP mirror sites or
  directly at <http://www.delorie.com/pub/djgpp>. For help on which

NOTES-UNIX.md

@@ -2,7 +2,7 @@ NOTES FOR UNIX-LIKE PLATFORMS
 =============================
 
  For Unix/POSIX runtime systems on Windows,
- please see [NOTES-Windows.txt](NOTES-Windows.txt).
+ please see [NOTES-WINDOWS.md](NOTES-WINDOWS.md).
 
  OpenSSL uses the compiler to link programs and shared libraries
  ---------------------------------------------------------------

NOTES-WINDOWS.md

@@ -1,9 +1,6 @@
 NOTES FOR WINDOWS PLATFORMS
 ===========================
 
- (This file, like the others, is in "markdown" format, but has a ".txt"
- extension to make it easier to view/edit on Windows.)
-
  There are various options to build and run OpenSSL on the Windows platforms.
 
  "Native" OpenSSL uses the Windows APIs directly at run time.

README.md

@@ -105,13 +105,13 @@ detailed instructions about building and installing OpenSSL. For some
 platforms, the installation instructions are amended by a platform specific
 document.
 
- * [NOTES-Android.md](NOTES-Android.md)
+ * [NOTES-ANDROID.md](NOTES-ANDROID.md)
  * [NOTES-DJGPP.md](NOTES-DJGPP.md)
- * [NOTES-Unix.md](NOTES-Unix.md)
+ * [NOTES-UNIX.md](NOTES-UNIX.md)
  * [NOTES-VMS.md](NOTES-VMS.md)
- * [NOTES-Windows.txt](NOTES-Windows.txt)
- * [NOTES-Perl.md](NOTES-Perl.md)
- * [NOTES-Valgrind.md](NOTES-Valgrind.md)
+ * [NOTES-WINDOWS.md](NOTES-WINDOWS.md)
+ * [NOTES-PERL.md](NOTES-PERL.md)
+ * [NOTES-VALGRIND.md](NOTES-VALGRIND.md)
 
 Specific notes on upgrading to OpenSSL 3.0 from previous versions, as well as
 known issues are available on the [OpenSSL 3.0 Wiki] page.