Adding credential_uid as an observable type, misc Changelog fixes

[floydtree]

Related Issue: n/a

Description of changes:

1. Adding credential_uid as an observable type, type_id 19.
2. Misc Changelog fixes

[mikeradka]

The schema update itself looks good, but just a sanity check - is this why 19 was omitted in the first place, or was there some oversight or some other reason for that?

[floydtree]

The schema update itself looks good, but just a sanity check - is this why 19 was omitted in the first place, or was there some oversight or some other reason for that?

We never reached 19 prior to this. The gap existed because of the initial segmentation that we had in place for scalar vs object observable entities.