Merge branch 'nyov/wiki' into 'master'

Allow cloning wiki from './all'

This enables cloning the wiki by adding a `wiki.yes` file for `all`.

As the setup stands, it would require @divVerent to mirror the repo first at de.x.o before this can work.
(Alternatively re-enable gitlab as a valid location named `lab` and `./all update -l lab` to test or use it.)

See merge request !1