docs: Adds trivial changes section to contributing guidelines

[darigovresearch]

Following details from pull request #3302

Would resolve #3352 if merged

[ludamad]

Thank you, although this doesn't spell out what the current policy is, which after some thought is that all changes are welcome but we reserve the right to redo minor PRs in our own PR due to not wanting to encourage trivial changes to farm metrics. The idea with not adding it immediately is that people can continue to make pull requests as usual, just with the policy we'll get them in through a remade PR once ready, so we can potentially leave it as well and we'll message people case-by-case when this has happened

[ludamad]

Closed as not planned. Current thinking is we just communicate this as people open PRs but nothing is discouraged and it's just a technical detail of the merge

[darigovresearch]

Thanks for the update @ludamad !