Add version note for [workspace] section

[gamila-wisam]

fixes #4506
Adds a compatibility note to the [workspace] section in docs/src/toml-files.md indicating that workspaces require Julia 1.12+.

[gamila-wisam]

This PR adds the same compatibility note for [workspace] as in #4581, but places it right after the section heading so it is immediately visible.
The previous PR seems to have unrelated CI failures (docs-only changes should not affect tests).
This should resolve #4506.

[inkydragon]

Like, I am now reading up on the [workspace] section ...

You may need to check all these sections to see
if compatibility notes need to be added.
I recommend starting with Julia v1.10 (the current LTS version),
or even earlier versions like Julia v1.6 (the previous LTS version).

[gamila-wisam]

Hi @inkydragon ,
I’ve added the compatibility notes for the other Project.toml sections.
When you have a chance, could you please review the changes and let me know if everything looks good? Thanks!

(to clarify, the CI has passed.
The codecov/projectFailing failing is appearing because this PR only changes documentation, the [sources] compatibility note was moved to match the style of other sections.
This caused a slight change in coverage report line offsets.
so no broken tests and everything is working as expected.)

[gamila-wisam]

Docs CI tests passes , but nightly tests fails due to an upstream issues(including GitHub fetch errors), i already rebased onto current master, but the nightly fails remains.

[gamila-wisam]

@KristofferC Hi, can you take a look when you have a moment please?