Add note emphasizing compiler/version support

Author: Felicity Chapman

docs/ql-documentation/support/index.rst

@@ -1,7 +1,7 @@
 Supported languages and frameworks
 ##################################
 
-These pages describe the languages and frameworks supported in the latest release of QL and LGTM. 
+These pages describe the languages and frameworks supported in the latest enterprise release of QL and LGTM. 
 Users of `LGTM.com <https://lgtm.com/>`_ may find that additional features are supported because it's updated more frequently.
 
 For details see:

docs/ql-documentation/support/language-support.rst

@@ -4,6 +4,10 @@ Languages and compilers
 QL and LGTM version |version| support analysis of the following languages compiled by the following compilers.
 
 Note that where there are several versions or dialects of a language, the supported variants are listed.
+If your code requires a particular version of a compiler, check that this version is included below. 
+Customers with any questions should contact their usual Semmle contact with any questions. 
+If you're not a customer yet, `contact us <info@semmle.com>`_ 
+with any questions you have about language and compiler support.
 
 .. csv-table::
      :file: versions-compilers.csv