Complete example and docs for "update-infra" workflow

[pravindahal]

It is implemented in helloworld; needs verification and docs: https://github.com/coopnorge/helloworld/tree/main/.github

[pravindahal]

This was merged to the main setup here: https://github.com/coopnorge/helloworld/pull/3326

It can perhaps be made into a preset.

[AtzeDeVries]

this has been fixed.