Add footer metadata detailed guides, supporting pages and collections

For consistency I have added footer metadata to the above pages
• include partial to pages
• add footer_meta: true local to header
• nest styles for detailed guides to correct layout issues
• bumped toolkit gem version to include measurement variables used

https://www.agileplannerapp.com/boards/105200/cards/6292
Nest styles for detailed guidance in desktop media query to fix layout
Merge pull request #1827 from alphagov/add-footer-metadata

Add footer metadata detailed guides, supporting pages and collections