Some more updates to the mod_lua doc:

- link to the Lua web site
- Lua modules are properly refered to as 'packages'
- intro to writing hooks in Lua
- remove unnecessary indentation from examples


git-svn-id: https://svn.apache.org/repos/asf/httpd/httpd/trunk@940246 13f79535-47bb-0310-9956-ffa450edef68