Support setting repository url for source links instead of always using git origin remote.

[lukaswelinder]

• I have checked issues with enhancement label and found no duplicates

Problem

When generating documentation, the "defined in" links always point to the git origin remote, which becomes a pain when trying to update docs on an upstream repository.

Suggested Solution

Allow user to define which git remote or url they wish to use for the repository.

[Gerrit0]

The soucefile-link plugin does a pretty good job of this already

[Gerrit0]

I've changed my mind ^

TypeDoc should support this natively. Users shouldn't need to install a plugin to update docs for an upstream repo.

[Gerrit0]

With 0.17.0-1 (beta) you can set the remote with --gitRemote