chore: adding docs conventional commit, adapt conditional labeling

[signorecello]

Description

Adds the docs conventional commit, and uses it to trigger conditional labelling

Problem*

Not exactly a problem, just another way to trigger the documentation label and provide a preview

Summary*

• Adds a docs type on the CONTRIBUTING guide.
• Refactors the build-docs workflow to check for PR title and apply label if it matches the type

[TomAFrench]

Can you make sure that these PRs won't appear in the changelog? chore PRs don't get included there.

[kevaundray]

We have something similar on the aztec-packages repo, where sometimes folks use chore(docs): and other times docs: -- I'd prefer to have only one way to do this and we standardize around that

[signorecello]

I'll check what they have and copy it, I also want it to be consistent

[signorecello]

So, apparently docs should be a "scope" and not a type. Being that we don't currently care about scopes yet. This kind of makes sense, as changes in the docs shouldn't trigger any versioning.

I'll remove this from the conventional commits

[signorecello]

actually I'll drop the PR because it's useless now lol