clarify in what situations "however" is allowed according to Docs writing guidelines

[WakaJoekoe]

Issue description: "however" is one of the 8 banned words according to the writing guidelines. It also says that it has "some uses", but it's never explained in what case it may be used.

URL to the documentation page (if already existing): https://docs.godotengine.org/en/stable/community/contributing/docs_writing_guidelines.html#ban-these-8-words

[Calinou]

cc @NathanLovato

As I understand it, you're allowed to use "however", but you should use it sparingly. It probably shouldn't be used more than once per page (maybe twice in long pages) :slightly_smiling_face: