Updating release notes

Author: mikefarah

release_notes.txt

@@ -1,3 +1,8 @@
+4.29.1:
+  - Fixed Square brackets removing update #1342
+  - XML decoder/encoder now parses directives and proc instructions (#1344). Please use the new skip flags [documented here](https://mikefarah.gitbook.io/yq/usage/xml) to ignore them.
+  - Bumped Go compiler version
+
 4.28.2:
   - Fixed Github Actions issues (thanks @mattphelps-8451)
   - Fixed bug - can now delete documents #1377