Add note to readme about CWE coverage tables

Author: ethanpalm

docs/codeql/query-help/readme.md

@@ -2,7 +2,9 @@ CodeQL query help Sphinx documentation
 --------------------------------------
 
 This project supplies the configuration and some boiler plate
-index files for the CodeQL query help documentation.
+index files for the CodeQL query help and CWE coverage documentation.
 
 The query help itself is automatically generated by the 
-"Generate CodeQL query help documentation using Sphinx" workflow.
+"Generate CodeQL query help documentation using Sphinx" workflow.
+
+The CWE coverage tables are generated and appended to pages by the "Docs generate query help" workflow in the `semmle-code` repository.