Add a release note (feature)

Comes with the MSYS2 runtime (Git for Windows flavor) based on [Cygwin
v3.5.6](https://inbox.sourceware.org/cygwin-announce/20250126210031.2173904-1-corinna-cygwin@cygwin.com/)
(Git for Windows skipped
[v3.5.5](https://inbox.sourceware.org/cygwin-announce/20241220181956.2204526-1-corinna-cygwin@cygwin.com)
because it failed to pass Git's test suite).

Signed-off-by: gitforwindowshelper[bot] <gitforwindowshelper-bot@users.noreply.github.com>

ReleaseNotes.md

@@ -46,6 +46,7 @@ Git for Windows is distributed with other components yet, such as Bash, zlib, cu
 * Comes with [cURL v8.11.1](https://curl.se/changes.html#8_11_1).
 * Comes with [MinTTY v3.7.7](https://github.com/mintty/mintty/releases/tag/3.7.7).
 * New Git for Windows installation [now default to the Windows-native HTTPS transport backend](https://github.com/git-for-windows/build-extra/pull/586).
+* Comes with the MSYS2 runtime (Git for Windows flavor) based on [Cygwin v3.5.6](https://inbox.sourceware.org/cygwin-announce/20250126210031.2173904-1-corinna-cygwin@cygwin.com/) (Git for Windows skipped [v3.5.5](https://inbox.sourceware.org/cygwin-announce/20241220181956.2204526-1-corinna-cygwin@cygwin.com) because it failed to pass Git's test suite).
 
 ### Bug Fixes