Support for custom gitUrlPattern or custom repository types

[ChristophLindemann]

It would be nice if one could provide a custom _gitUrlPattern, to generate custom URLs for "View source" and "Improve this Doc"

This would enable us to support "View source" for other repositories then VSO or Github hosted ones.

This would for example enable us to use a special pattern when building a pull request, so that the resulting "view source" would refer the pull request view for a file, instead of the repository view of the file. So a reviewer could look at the generated API documentation, and if he finds something worth commenting, he could press the "View source" button and be taken to the pull-request (instead of beeing taken to something like refs/pull/ repository view)

At the same time you could also use this to support other repository types then Git, like Subversion, P4 or TFVC.

[superyyrrzz]

In DocFX vCurrent, you can custom the related logic in template to support another repo type. You can also make it support your pull request case.

In DocFX v3, it will support similar features like _gitUrlPattern. If you want to support another pattern, we'd encourage you to create a pull request to DocFX to extend existing _gitUrlPattern. This could benefit later users from the burden to try out a custom rule. As the number of repo types is quite limited, we still cannot see it is a strong requirement to expose an extension point here. It is enough to add one by one.

Of course, the limitation is that you cannot achieve your pull request requirement with this. IMO, a PR's edit button can point the article with commit id like https://github.com/{owner}/{repo}/blob/{commit_id}/{path} to help review the source file. Both the CMS behind docs.microsoft.com and netlify deploy preview shares the same behavior. In v3, this could be a simple config work.

/cc @OsmondJiang @yufeih