Update Code of conduct for modding and mapping

[MChecaH]

First change of the suite of changes prepared to improve the Wiki's current modding resources.

This one is focused on simplifying, rewording, and improving the current Modding Code of Conduct article. The contents deleted will be moved to their respective articles, decluttering the CoC in turn.

The project is being tracked in the following Issue and the following osu! Discord server thread.

Note for later; The broken wiki link in Modding will need to be changed later by the new guide, once it is ready.

Self-check

• The changes are tested against the contribution checklist
• The changes are reviewed by the team working on the rework. Thread
• The changes are reviewed by the team who will enforce them (Mainly NAT and map/mod GMTs). Thread

[Userlog2]

No more to say outside the comments I made.

[cl8n]

last review for me

[cl8n]

oh also it's not in the change set but I would remove "and general ranking criteria" from the intro... doesnt really make sense because the rules apply to different things, and it's just unnecessary for that sentence to work well

[cl8n]

approval for article itself, but ci says some other links need to be adjusted

[cl8n]

(with the expectation that the context in /Modding will be improved in a future PR)