[docs] Add instructions for deploying docs without a release

[cherniavskii]

• I have followed (at least) the PR section of the contributing guide.

[mui-bot]

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https://deploy-preview-36301--material-ui.netlify.app/

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[oliviertassinari]

Nice 👍

[oliviertassinari]

I usually do this:

Suggested change

	git push
	git push material-ui-docs HEAD:latest

When your work on an alpha branch, both repositories use next for the name of the branch. It can be ambiguous.

[oliviertassinari]

I usually do:

Suggested change

	git checkout --track material-ui-docs/latest
	git reset --h material-ui-docs/latest

to not have to care about branches. If I run git checkout --track material-ui-docs/latest it tells me that the branch already exists.

[cherniavskii]

Good catch, git checkout isn't a good solution in this case.
git reset --h material-ui-docs/latest has a drawback too - it will reset the branch you're currently on to the material-ui-docs/latest, so you might lose the commits on this branch if the branch is local-only.

We can do this instead:
git switch --detach material-ui-docs/latest
It will not impact your current branch since it only detaches the HEAD.
After adding more commits, you can push it to material-ui-docs/latest with:
git push material-ui-docs HEAD:latest

What do you think?

[mapache-salvaje]

text looks great! Thanks for putting this together @cherniavskii !