add docs deploy preview

[robbymilo]

for https://github.com/grafana/website/issues/10101

What is this feature?

This PR adds a workflow to deploy the output of the make docs command to a public deploy preview.

Why do we need this feature?

Docs contributors will no longer need to run make docs on their machine, as they will be able to view the deploy preview instead.

Who is this feature for?

Everyone.

[jdbaldry]

I wonder if the maintainers would be happy with https://github.com/orgs/grafana/teams/docs-tooling/ becoming CODEOWNERS of https://github.com/grafana/alloy/pull/2268/files#diff-fcf14c4b7b34fe7a11916195871ae66a59be87a395f28db73e345ebdc828085bR12-R18

We'll need the team to be given write access to the repository

[ptodev]

I suppose that the URL varies, and we'd need to check the CI log for the exact address each time?

Regarding the code owners - I'd be happy to change it to the docs tooling team. It makes more sense than assigning it just to one particular person anyway 😆 And it works better as people join and leave the team.

[robbymilo]

Thanks @ptodev! Could you let me know when https://github.com/orgs/grafana/teams/docs-tooling/ is added to the repo? I will go ahead and update the codeowners in a different PR.

[jdbaldry]

I suppose that the URL varies, and we'd need to check the CI log for the exact address each time?

A bot posts the URL as a comment as part of the workflow so you don't need to worry about checking the logs :)

[clayton-cornell]

Happy to see this in Alloy. It's SUPER useful in the other repos.

[wildum]

This is awesome, thanks a lot!