[Meta] Allow public edits for wiki

[hXtreme]

The wiki page currently doesn't allow other users to make edits or fixes.

[lhartikk]

I would gladly accept PR:s for the wiki, but I'm not sure if that is possible..

[hXtreme]

Wikis should be editable without prs if the repo owner sets it up.

See https://github.com/inorichi/tachiyomi/wiki

On that wiki there's an edit button that anyone can use to edit the wiki.

I'll try to look for some instructions on how to set that up and link them here.

Meanwhile
this is what I get if I try to edit this repo's wiki.

[hXtreme]

Link for setting up public editing of wiki : https://help.github.com/en/github/building-a-strong-community/changing-access-permissions-for-wikis