chore: section clarity, harden API, providers

[toddbaert]

Marking Evaluation API and Providers hardening and a few non-functional changes here that improve structure.

specifically:

• explicitly mark and number all sections
• section headings have consistent numbering (provider section numbering was different than the other docs)
• removed "draft" language

An alternative to marking all of provider and evaluation API as hardening would be just marking all existing sections therein as hardening, which might be better since we'd have to do that anyway if we added a new experimental section.

see: #146 for more on release goals.

[beeme1mr]

Changing the spec version numbers may require numerous changes to tests in various SDKs. That doesn't necessary mean we can make the change but we should be aware of the impact.

[toddbaert]

Changing the spec version numbers may require numerous changes to tests in various SDKs. That doesn't necessary mean we can make the change but we should be aware of the impact.

100%. I know this changes some tests, but this change should actually reduce such thrashing in the future and makes things more consistent. Provider was the only section where the requirements didn't have 3 decimal places.

[toddbaert]

An alternative to marking all of provider and evaluation API as hardening would be just marking all existing sections therein as hardening, which might be better since we'd have to do that anyway if we added a new experimental section.

[toddbaert]

@justinabrahms do you have any objections to this? (I volunteer to absorb the test-renumbering in the java-sdk)