s/cacheing/caching/

s/cacheing/caching/
Improve layout.

Add some missing <module> tags.
Add some missing <directive> tags.
Add some missing <directive module=...> links
Add the name of the directive in <default>, so that 'quickreference.html' is generated correctly.
In the AuthnCacheContext directive, fix the way 'directory' and 'server' are displayed. They are key-words and should not be in italic.

(r1865402 in trunk)

git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/branches/2.4.x@1865403 13f79535-47bb-0310-9956-ffa450edef68