Go over GitHub settings

[iv-p]

Make sure GitHub settings are reasonable and possibly google what they should be.

For example forking is disabled, but should be enabled.

[dimitarvdimitrov]

things changed:

• removed merge commits as an option when merging PRs (only squashing and rebase&merge are available now)
• automatically delete branches after merging
• require branches to be up to date before merging to master
• accept content reports from collaborators and prior contributors
• afaik only getapid members have push access, so nothing changed regarding push access

things not changed:

• couldn't enable forking. It's grayed out, I guess it will become available once we make the repo public.
• FYI, we don't have a project "social media preview" image, need to update this once we have a logo

@iv-p @morwoen can once of you close this if you're happy with what's done