Mention that snippets can not define multiple types or areas

[DanielRuf]

Q	A
Fixed tickets	fixes #issuenum
Related PRs	sulu/sulu#prnum
License	MIT

What's in this PR?

This makes it clear, that there is currently no support for multiple types and areas.

See also:

• https://github.com/sulu/sulu/blame/2.5/src/Sulu/Bundle/SnippetBundle/Controller/SnippetController.php#L167
• https://github.com/sulu/sulu/commit/462f283882ac71d0834d1391904b5de99e15e179
• https://github.com/sulu/sulu/commit/6bb57558d019774fc4cf639476f6cda00ee00531
• https://github.com/sulu/sulu/pull/4816#issuecomment-544495549

Why?

It's still not mentioned in the docs.

[alexander-schranz]

Thx for the pull request. Can you rebase it to the 2.4 branch as that is currently the lowest supported version where this additional also make sense.

git rebase -i origin/2.x --onto origin/2.4

[DanielRuf]

Can you rebase it to the 2.4 branch as that is currently the lowest supported version where this additional also make sense.

git rebase -i origin/2.x --onto origin/2.4

Done.

[alexander-schranz]

@DanielRuf Thank you!