Doc'ing Tux Paint Merge Request #12 in CHANGES.txt

"Add Appstream metadata, and port from intltool to gettext"
https://sourceforge.net/p/tuxpaint/tuxpaint/merge-requests/12/

docs/CHANGES.txt

@@ -26,6 +26,29 @@ http://www.tuxpaint.org/
       on Windows.
       TOYAMA Shin-ichi <dolphin6k@wmail.plala.or.jp>
 
+    * Merge "tuxpaint.desktop" file at build time (rather than as a
+      manual step)
+      (See https://sourceforge.net/u/wjjjjt/tuxpaint/ci/b4aa697474e1cc60b6faac80297cc66a602f54fd/)
+      Will Thompson <https://sourceforge.net/u/wjjjjt/profile/>
+
+    * Adding "2DGraphics" (and hence "Graphics") and "KidsGame" (and hence
+      "Game") to the categories listed in "tuxpaint.desktop" launcher for
+      FreeDesktop systems (e.g., Linux)
+      Will Thompson <https://sourceforge.net/u/wjjjjt/profile/>
+
+    * Remove "intltool" dependency. (Thanks to this, no need for
+      "tuxpaint.desktop.in".  It involved rewriting "update-po.sh"
+      to invoke 'xgettext' and 'msgfmt' rather than 'intltool' commands.)
+      (See https://sourceforge.net/u/wjjjjt/tuxpaint/ci/31412499690cc3c4c8729d7100e241a346b5741e/)
+      Will Thompson <https://sourceforge.net/u/wjjjjt/profile/>
+
+    * Added "appstream" metainfo file (used by software centers like
+      GNOME Software and KDE Discover) to display info about an app.
+      (See https://sourceforge.net/u/wjjjjt/tuxpaint/ci/74506214e74d326e7515af3e0bfde41161d1531f/)
+      For https://sourceforge.net/p/tuxpaint/feature-requests/172/
+      Richard Hughes <https://sourceforge.net/u/hughsie/profile/>
+      and Will Thompson <https://sourceforge.net/u/wjjjjt/profile/>
+
   * Documentation updates:
     ---------------------
     * Update macOS build instructions for SDL2.0.