Improve .gitignore comment

Author: spl

.gitignore

@@ -1,9 +1,8 @@
-# Ignore everything first. Several things are brought over by the
-# `prepare-release.sh` script, which causes a `git` branch change, but `git`
-# won't delete from the working directory.
+# Ignore everything first. Many items are in the `main` branch and not in the
+# release branch.
 /*
 
-# Don't ignore only the files and directories included in the release.
+# Don't ignore only the items included in the release branch.
 !LICENSE.md
 !README.md
 !action.yml