Docs: Remove reference to checking out main branch

We are no longer including information about how to check out
github/codeql, so this paragraph doesn't fit any more.

Author: aeisenberg

docs/codeql/codeql-cli/upgrading-codeql-databases.rst

@@ -4,21 +4,16 @@ Upgrading CodeQL databases
 ==========================
 
 As the CodeQL CLI tools and queries evolve, you may find that some of your
-CodeQL databases become out of date. You must upgrade out-of-date databases 
+CodeQL databases become out of date. You must upgrade out-of-date databases
 before you can analyze them.
 
 Databases become out of date when:
 
 - For databases created using the CodeQL CLI, the version of CLI tools used to
-  create them is older than your copy of the CodeQL queries. 
+  create them is older than your copy of the CodeQL queries.
 - For databases downloaded from LGTM.com, the CodeQL tools used by LGTM.com to create
   that revision of the code are older than your copy of the CodeQL queries.
 
-The ``main`` branch of the CodeQL queries is updated more often than both the
-CLI and LGTM.com, so databases are most likely to become out of date if you use
-the queries on this branch. For more information about the different versions of
-the CodeQL queries, see ":ref:`Getting started with the CodeQL CLI <local-copy-codeql-queries>`." 
-
 Out-of-date databases must be upgraded before they can be analyzed. This topic
 shows you how to upgrade a CodeQL database using the ``database upgrade``
 subcommand.