Rename the directory structure and resources
Fix spelling of centred
Merge pull request #333 from alphagov/user-centred-design

Fix spelling of centred
Use relative links

Make it link to the correct thing in development and preview.

Conflicts:
	service-manual/content-designers/transactions-style-guide.md
Merge pull request #334 from alphagov/use-relative-links

Use relative links
Fix broken URLs

This commit:

- moves GDS URLs over their redirects to the appropriate place
- fixes the link on the ideal alpha guidance
- changes some external hostnames to HTTPS
Merge pull request #337 from alphagov/fix-urls

Fix broken URLs
Updated entire DbD assessments pages

* add 2 new pages
* deleted 2 out-of-date pages
* inserted team updates in 4  pages, including index page