Configurable social links

[TheElectronWill]

If you look at the static documentation of many projects (for instance Cats or Bloop) you'll find a link to their GitHub repository, Twitter account, Discord server, etc.

It would be useful to provide a CLI option or a configuration file for this. Those links could go in the left column and/or in the footer.

[abgruszecki]

I agree that this looks useful. However, it looks like something best done as part of a templating engine for static site content, and I'm not sure if that should be strictly a part of the doctool.

@romanowski already has some ideas about how to include a templating engine.