Remove Guidance suggestion that resolvers validate against the test suite

[jandrieu]

The specification says:

In practice, implementers validate their resolver against the
			<a href="https://github.com/w3c-ccg/did-resolution-mocha-test-suite">DID Resolution Test Suite</a> which exercises
			normative MUSTs and error conditions (such as invalid DIDs, deactivated DIDs, unsupported methods,
			relative URL expansion, etc.) to ensure that client applications can reliably depend on correct resolution behavior
			across different DID methods.

However, that is not the purpose of the test suite--which is to test the features of the specification. The implication creates a misunderstanding of the purpose of the suite, suggesting that it is a compliance mechanism for evaluating the quality of the software. It isn't and shouldn't be interpreted that way, as doing so creates security-impacting misconceptions.

This was fixed in PR#311 and #315, but those are being deconstructed.

[swcurran]

As this is unlikely to be addressed in the PRs referenced -- #311 or #315 -- suggest that you put a targeted PR for the specific paragraph. Perhaps just changing the start to "Implementers are encouraged to validate their..." is sufficient to remove any implied requirement or purpose.