Add a release note (feature)

Comes with [Git
v2.48.1](https://github.com/git/git/blob/v2.48.1/Documentation/RelNotes/2.48.1.txt).

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Author: dscho

ReleaseNotes.md

@@ -47,6 +47,7 @@ Due to persistent maintenance challenges and the community's limited engagement
 
 ### New Features
 
+* Comes with [Git v2.48.1](https://github.com/git/git/blob/v2.48.1/Documentation/RelNotes/2.48.1.txt).
 * 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 v3.5.7](https://inbox.sourceware.org/cygwin-announce/20250129212153.2589012-1-corinna-cygwin@cygwin.com/T/#u) (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, and [Cygwin v3.5.6](https://inbox.sourceware.org/cygwin-announce/20250126210031.2173904-1-corinna-cygwin@cygwin.com/) was superseded too quickly).