Doc doc updates.

Author: rouilj

CHANGES.txt

@@ -158,6 +158,9 @@ Features:
   reindex the first 1000 issues while reporting any missing issues
   in the range. Also completion progress is reported when indexing a
   specific class.
+- doc updates: add explanation for SQL code in 1.3.3->1.4.0 upgrade.
+  document schema table in rdbms backends and how to dump/extract
+  version from them. (John Rouillard)
 
 2022-07-13 2.2.0