Disable some CI checks on docs updates

[thomas-bc]

Originating Project/Creator
Affected Component
Affected Architectures(s)	CI
Related Issue(s)
Has Unit Tests (y/n)
Builds Without Errors (y/n)
Unit Tests Pass (y/n)
Documentation Included (y/n)

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Change description

Disable the build/test/static code analysis checks on PRs that only touch docs/** and **.md files.

Rationale

We often get PRs on documentation, which trigger the entire CI check suite. I propose we disable some of those checks on these occasions, which are computationally intensive and quite irrelevant. They also slow down the review process for PRs that could be merged in a matter of minutes.

A case against this PR:

Sometimes checks will fail on documentation PRs for reasons that are unrelated (e.g. the RPI agents are unavailable, something broke upstream/fprime-tools etc...).
The case could be made that we should know as soon as possible when this happens, and therefore we should not disable those checks. Which I don't disagree with tbh. This is up for debate, totally fine if we don't want to accept this change.

[LeStarch]

I love this!

Another case against this PR could be "what if someone adds a check (e.g. broken link scan) to an existing action. It might not get triggered".

I don't but that argument nor the one you presented. I think, however; we should always run python and spelling checks....see inline comment.

[thomas-bc]

Agreed. If we get to modifying workflows down the line, the restriction can always be reversed. Workflows should be tightly scoped though, adding URL checks within a build workflow would be -in my humble opinion- a questionable design.