DDSSEC_ — Section 8.3.2.9.1 (Authentication plugin interface) should not be under 8.3.2.9 (Unauthenticated DomainParticipant entities)

The section 8.3.2.9.1 "Authentication plugin interface" should not be nested under "Unauthenticated DomainParticipant entities". Rather it should be parallel section.
The subsections 8.3.2.9.2 "Type: ValidationResult_t" to 8.3.2.9.17 "Operation: return_sharedsecret_handle" should be subsections of Authentication plugin interface".

Suggested change:
Change Section 8.3.2.9.1 (Authentication plugin interface) to be section 8.3.2.10. Then current section 8.3.2.10 (AuthenticationListener) becomes Section 8.3.2.11.

The current subsections 8.3.2.9.2 "Type: ValidationResult_t" to 8.3.2.9.17 "Operation: return_sharedsecret_handle". Should become subsections of the new 8.3.2.10 (Authentication plugin interface) and take numbers 8.3.2.10.1 (for "Type: ValidationResult_t") to 8.3.2.10.16 (for "Operation: return_sharedsecret_handle").

Change Section 8.3.2.9.1 (Authentication plugin interface) to be section 8.3.2.10.

Make the changes suggested in the issue description