Add source_url so ex_doc can generate links to source code

[axelson]

See docs:
https://hexdocs.pm/ex_doc/0.37.3/Mix.Tasks.Docs.html#module-configuration

Also minor updates to ex_doc and earmark_parser

Right now the PostHog docs don't have a link to source code:

Many libraries on hexdocs do have links and they look like (https://hexdocs.pm/phoenix/Phoenix.Socket.html#assign/3):

Adding source_url and push up a git tag for each release will fix this.

Note: it is also possible to publish an updated version of the docs without releasing a new version of the package.

[rafaeelaudibert]

Hey @axelson!

Adding source_url and push up a git tag for each release will fix this.

Where did you find the fact that we need to push up a git tag for each release? We're not doing that right now, and Im happy to change CI to make that work, but it'd be good to see documentation explaining how that works (the link you linked doesn't say that anywhere, but neither does it say what source_url does to be honest)

[rafaeelaudibert]

Once we merge this, I'll also merge a follow-up PR including some more changes to make our hexdocs docs a little bit nicer (logo, favicon, banner, etc)

[axelson]

Where did you find the fact that we need to push up a git tag for each release? We're not doing that right now, and Im happy to change CI to make that work, but it'd be good to see documentation explaining how that works (the link you linked doesn't say that anywhere, but neither does it say what source_url does to be honest)

Hi! 👋

I'm not sure where I initially learned it. It was probably because I encountered a library that set :source_url but did not push git tags so the generated source code links resulted in 404's.

I looked around for official documentation of this requirement but I was not able to find any so I have created a PR to add it at: elixir-lang/ex_doc#2109

[rafaeelaudibert]

Hey!

Thanks for that! I'll wait for confirmation from José before we merge this. If he's correct - and I doubt Valim would be wrong there - we'll also need to update our script to include the ref config he's mentioning.

[axelson]

The PR isn't merged yet (although I did push up improved wording today) but the info has been confirmed so I think this change can be considered unblocked.

[rafaeelaudibert]

I see José just merged it. I'll merge this PR, but it wont outright work because we're missing source_ref AND tagging the version. Im working on a PR to add that. Once we have both, we'll have links in our docs!

Thanks for your effort here @axelson!