More prominent "Admin" link + small layout tweaks and fixes

[SchlenkR]

When I was searching for fsprojects policies / intentions / mission statemente, etc., I saw the "Admin" link, but never ever clicked on it, since I understood "Admin" in a way like "It's a link for administrators" and not "a link for administrative concerns in general". Maybe this PR helps others who might experience the same issue.

---

Changes:

• Clarified intention of the "admin" link and moved it
• Added link to GitHub
• Layout changes (moved stars / watchers links in project box)
• Layout fix (use the space directly underneeth 'main')
• Small layout changes (optical)

[SchlenkR]

BTW: For the very last layout tweak, it wasn't possible to test it with a complete page reload, because my GitHub API access limit was reached. So better to test it again if the PR should be merged.