rename README.Windows.md to README.md

The file is solely about compiling for Windows, not for using it on
Windows or anything else. SO make it clearer.

A second advantage is that GitLab won't get confused. GitLab
automatically places a link called "ReadMe" on the overview page. It
links to the first file matching the glob "README*" in alphabetical
order. As "README.Windows.md" sorts lower than "README.md", the link
was pointing to a file explaining to the user how to compile for
Windows. Not the ideal landing page for a repository.

tools/development/bump_version_set_code_name.sh

@@ -74,7 +74,7 @@ function update_files {
 
   perl -pi -e 's/^(AC_INIT.*\[)'$FROM'(\].*)/${1}'$TO'${2}/' configure.ac
   perl -pi -e 's/^MKVToolNix '$FROM'$/MKVToolNix '$TO'/' README.md
-  perl -pi -e 's/^Building MKVToolNix [0-9.]+/Building MKVToolNix '$TO'/i' README.Windows.md
+  perl -pi -e 's/^Building MKVToolNix [0-9.]+/Building MKVToolNix '$TO'/i' Building.for.Windows.md
   perl -pi -e 's/define PRODUCT_VERSION .*/define PRODUCT_VERSION \"'$TO_NSI'\"/' installer/mkvtoolnix.nsi
   perl -pi -e "s{#define VERSIONNAME.*}{#define VERSIONNAME \"${CODENAME}\"}" src/common/version.cpp
 }

tools/windows/setup_cross_compilation_env.sh

@@ -4,7 +4,7 @@ set -e
 
 # Creates a tree with all the required libraries for use with the
 # mingw cross compiler. The libraries are compiled appropriately.
-# Read the file "README.Windows.md" for instructions.
+# Read the file "Building.for.Windows.md" for instructions.
 
 #
 # SETUP -- adjust these variables if neccessary.