Replace the github 'edit this page' links with gitlab links

Now it is easier to open accounts on this gitlab instance.

Also, since our website branches got protected, we need to push a merge request to the gitlab repo to be able to merge changes.

So it would be easier to review and merge updates if users submit their merge requests on gitlab.

One way of improving this is to change the 'Edit this page' link at the bottom of some of the websites, that is currently pointing to our github mirror, and make it point to the repos in this gitlab instance.

Changes should be done in:

• Support.tpo
• TB-manual.tpo
• Community.tpo