CodeQL docs migration: Delete ql-spec Sphinx project

Author: shati-patel

docs/language/README.rst

@@ -18,8 +18,7 @@ Project structure
 The documentation currently consists of the following Sphinx projects:
 
 - ``learn-ql``–help topics to help you learn CodeQL and write queries
-- ``ql-handbook``–a user-friendly guide to the QL language, which underlies CodeQL analysis
-- ``ql-spec``–formal descriptions of the QL language and QLDoc comments
+- ``ql-handbook``–an overview of important concepts in QL, the language that underlies CodeQL analysis
 - ``support``–the languages and frameworks currently supported in CodeQL analysis
 - ``ql-training``–source files for the CodeQL training and variant analysis examples slide decks