Update to Manual, directory tree, code of conduct, and more

[Mik-TF]

Related Issue

• To answer issue #438. This is a big change in backend, but the website is unchanged (except for urls).
• To fix issue #393
• put links to work with dashboard.grid.tf, and not next.dashboard.grid.tf

Staging version at https://www3.manual.grid.tf

Work Done

• adjusted the backend/directory tree to be in line with the new frontend/manual summary.md
• updated faq and removed outdated or duplicate info

Details

• this will obviously generate broken links elsewhere
  • we can use the website link checker for this as much as possible
  • @xmonader is also making sure we can quickly update the manual links on the dashboard.
• the manual directory was far from the real mdbook navigation
  • this results in complexity in working on the book and uneffective urls
• the new organization
  • makes it easier for future and present contributors to navigatge and make changes
  • has logical URLs (e.g. manual.grid.tf/documentation/dashboard/deploy/deploy.html)

[Mik-TF]

@xmonader ideally, we can accept/merge this PR at the same time that we push the new dashboard to main net.

Also, it would be effective to set the URLs of the new manual directory tree, instead of the old one.