[global] PR Template: Add section about linting

[schnatterer]

Is your feature request related to a problem ?

For me as a contributor, the process of linting is dragging on, because

• I have to wait for a maintainer to start the process.
• Then I might have fixed only 9 out of 10 findings
• So I wait again for a maintainer to start the process.
• Then a different linter tells me other findings. So I fix them.
• I wait again for a maintainer to start the process.

Describe the solution you'd like.

A simple solution would be to mention linting in the Pull Request template.
It could link to a document that tells me what linters are running and how I can run them locally.
I would prefer docker run commands for the linters as they run on all dev machines without prior setup and are deterministic.

Describe alternatives you've considered.

I'm sure there could be other options, like automatically run linters on commit.

Additional context.

FTR I discovered this behavior while working on #4818