LRDOCS-460 Introduce CDN section and document intro and info on using CDNs in Liferay
LRDOCS-460 Describe how to configure CDN for a portal instance
LRDOCS-460 Reorganize sections and add intro and conclusion text
LRDOCS-460 Minor Wordsmithing
LRDOCS-460 Update Image
Merge branch 'master' into cdn-docs

Conflicts:
	discover/deployment/articles/06-configuring-for-high-availability/03-configuring-for-high-availability-summary.markdown
	use/deployment/articles/06-configuring-for-high-availability/03-configuring-for-high-availability-summary.markdown
	use/deployment/articles/06-configuring-for-high-availability/04-configuring-for-high-availability-summary.markdown
LRDOCS-460 Add files into new 'discover' folder
LRDOCS-460 Remove old CDN docs from 'use' directory
LRDOCS-460 Re-add CDN images as well
Wordsmithing and ported to the user guide.
Merge branch 'pr-1035'