README: Use Markdown extension

Ensures proper rendering on GitHub [1] / GitLab, clarifies that Markdown
syntax is expected from contributors, and enables editor syntax
highlighting.

[1] https://github.com/openocd-org/openocd

Change-Id: Icaff52ed2bf7d6f32b5812b5aff1c081e8b7507a
Signed-off-by: Marc Schink <dev@zapb.de>
Reviewed-on: https://review.openocd.org/c/openocd/+/9388
Tested-by: jenkins
Reviewed-by: Antonio Borneo <borneo.antonio@gmail.com>

Makefile.am

@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0-or-later
 
-AUTOMAKE_OPTIONS = gnu 1.14
+AUTOMAKE_OPTIONS = foreign 1.14
 
 .DELETE_ON_ERROR:
 
@@ -63,8 +63,8 @@ EXTRA_DIST += \
 	BUGS \
 	HACKING \
 	NEWTAPS \
-	README.Windows \
-	README.macOS \
+	README.Windows.md \
+	README.macOS.md \
 	$(EXTRA_DIST_NEWS) \
 	Doxyfile.in \
 	LICENSES/license-rules.txt \

README.Windows.md

@@ -5,7 +5,7 @@ You can build OpenOCD for Windows natively with either MinGW-w64/MSYS
 or Cygwin (plain MinGW might work with --disable-werror but is not
 recommended as it doesn't provide enough C99 compatibility).
 Alternatively, one can cross-compile it using MinGW-w64 on a *nix
-host. See README for the generic instructions.
+host. See README.md for the generic instructions.
 
 Also, the MSYS2 project provides both ready-made binaries and an easy
 way to self-compile from their software repository out of the box.

README.macOS.md

@@ -41,7 +41,7 @@ MacPorts' libraries, so run configure like this:
   LDFLAGS=-L/opt/local/lib CPPFLAGS=-I/opt/local/include ./configure [options]
 
 
-See README for the generic building instructions.
+See README.md for the generic building instructions.
 
 If you're using a USB adapter and have a driver kext matched to it,
 you will need to unload it prior to running OpenOCD. E.g. with Apple

configure.ac

@@ -16,7 +16,7 @@ AS_IF([test "x$MAKEINFO" = "x"], [
 ])
 AC_SUBST([MAKEINFO])
 
-AM_INIT_AUTOMAKE([-Wall -Wno-portability dist-bzip2 dist-zip subdir-objects])
+AM_INIT_AUTOMAKE([foreign -Wall -Wno-portability dist-bzip2 dist-zip subdir-objects])
 
 AC_CONFIG_HEADERS([config.h])
 

doc/openocd.texi

@@ -239,7 +239,7 @@ needing a Git client:
 
 @uref{http://repo.or.cz/w/openocd.git}
 
-The @file{README} file contains the instructions for building the project
+The @file{README.md} file contains the instructions for building the project
 from the repository or a snapshot.
 
 Developers that want to contribute patches to the OpenOCD system are

tools/scripts/checkpatch.pl

@@ -1417,14 +1417,14 @@ sub top_of_kernel_tree {
 	if (!$OpenOCD) {
 	my @tree_check = (
 		"COPYING", "CREDITS", "Kbuild", "MAINTAINERS", "Makefile",
-		"README", "Documentation", "arch", "include", "drivers",
+		"README.md", "Documentation", "arch", "include", "drivers",
 		"fs", "init", "ipc", "kernel", "lib", "scripts",
 	);
 	} # !$OpenOCD
 	# OpenOCD specific: Begin
 	my @tree_check = (
 		"AUTHORS", "BUGS", "COPYING", "HACKING", "Makefile.am",
-		"README", "contrib", "doc", "src", "tcl", "testing", "tools",
+		"README.md", "contrib", "doc", "src", "tcl", "testing", "tools",
 	);
 	# OpenOCD specific: End