Split menu links and expanders

Will allow introduction of top-level descriptions
Rearrange somewhat

Site title is now clickable
Home section includes separate News and Testimonials
Add an external marker to external URLs
Clean up source-code menu

Also capitalise Bash correctly
Clean up download/install docs
Clean up support pages
Use common headings for all pages
Include a top-level documentation menu item
Reorganise tutorials and documentation
Add some guides
Improve news/testimonial formatting
Stop an internal link being flagged as external
Use meaningful IDs for FAQs
Fix link
Bring an adding services page back to website
Fix typo
Put back placeholder FAQs

We cannot rewrite anchors, so better they remain on the page in some form