ENH announce master to main migration

Author: beckermr

src/user/announcements.rst

@@ -5,6 +5,16 @@ Announcements
 
 Our announcements are published to an RSS feed `here <https://conda-forge.org/docs/news.rss>`_.
 
+2022
+----
+
+:2022-02-13: Default branch migration from ``master`` to ``main``
+
+    We will be migrating the default branches of all feedstocks and other ``conda-forge``
+    from ``master`` to ``main``. We do expect some minor hiccups while this migration is 
+    going on. If you encounter any problems, please comment on this Github 
+    `issue <https://github.com/conda-forge/conda-forge.github.io/issues/1162>`__.
+
 2021
 ----