Docs: Add `Separate mobile URLs` subsection

Inform users that, if they use separate URLs for desktop and mobile
users, they should consider helping search engine algorithms better
understand the configuration on their web site.

See also:

 * https://developers.google.com/webmasters/smartphone-sites/details#separateurls
 * https://developers.google.com/webmasters/smartphone-sites/feature-phones

Close #1504.
Make consistency changes

Change code indentation in `normalize.css` from 2 to 4 spaces. This
is done in order to be consistent with the indentation used in the
other files.
Update to Apache Server Configs 2.2.0
changed htaccess
cloned html5boilerplate and changed the index file to fit mobile screens