Added content to group data how to guide
Updated grouping how to guide links to point to correct page

- Custom directive anchor change removed
Updated getting started page links
Merge pull request #280 from tylerferguson/web-feature/grouped-data-how-to

Created grouped data how to guide
Add data processing how-to-guide

- Updates how-to controllers to set the page title
Move axis customisation how-to guide
Fix axis customisation how-to-guide
Update directive urls

Directives can now work on a server with a path:
`http://webserver/path/to/site/`.
Update axis page title

Also removes Prism and title setting from the how-to item
Fix issues raised in PR
Merge pull request #281 from matthewdunsdon/web/feature/group-processing-how-to

Add data processing how-to-guide
Update correlation how-to-guide
Remove redundant comment
Merge pull request #282 from matthewdunsdon/web/feature/correlation-how-to

Update correlation how-to-guide