add manual `workflow_dispatch`

[t-bltg]

Follow up of https://github.com/FluxML/MacroTools.jl/pull/189.

https://fluxml.ai/MacroTools.jl/dev looks good and was deployed correctly, now we need to run the documentation workflow on previous tags manually, this is what workflow_dispatch allows.

@cstjean, after this PR is merged, you can go to the Actions tab -> Documentation on the left -> Run workflow on the right -> Branch master (select Tags tab) -> select v0.5.10 -> and finally click Run workflow: it should build the docs for https://fluxml.ai/MacroTools.jl/stable (which now points to the obsolete v0.5.4 tag).

PR Checklist

• [x] Documentation, if applicable

[cstjean]

When I do that, I get

Workflow does not exist or does not have a workflow_dispatch trigger in this tag. Learn more about manual workflows

[t-bltg]

Weird, the docs workflow is similar to e.g. our Plots docs workflow https://github.com/JuliaPlots/Plots.jl/blob/master/.github/workflows/docs.yml.

Do we talk about the same as on the attached screenshot ?

[t-bltg]

Ha, maybe does not have a workflow_dispatch trigger in this tag means that it cannot be ran on a previous tag :/ I guess we will have to wait for a next release (dev docs is at least as expected).

[cstjean]

Ha, maybe does not have a workflow_dispatch trigger in this tag means that it cannot be ran on a previous tag :/ I guess we will have to wait for a next release (dev docs is at least as expected).

That's my guess too...