Setting: min trust to wiki-fy post

[techAPJ (Arpit Jalan)]

@codinghorror

allow tl3 users to wikify their own posts – but not other people’s?

@sam

“trust_level_to_allow_self_wiki”, cause in some internal setups or various sites people may be fine to allow TL1 or 2 to wikify own stuff

Okay, I sent a PR for this feature:

https://github.com/discourse/discourse/pull/3953