Revert "CM3: Add reStructuredText mode"

Causing rendering failures in some cases. Filed a bug upstream:

https://github.com/codemirror/CodeMirror/issues/2850

Change-Id: I0b4032d41b1fe5b9756ff59f752f5fce86634c41
Mention the push %l-parameter in the documentation

Change-Id: Icc564ca82c2e05d176f75ddfd3b11924dcabaabe
Fix broken formatting in Tomcat reverse proxy config documentation

Remove the unnecessary [TIP] block.

Fix the formatting of links.

Enclose example settings in backticks.

Add an anchor to make it easier to link the section from the release
notes.

Change-Id: I46dcc5cb6afc24c6717885a5ca5f1faa04d7a746