Adding canonical links to spec docs

[excentrickristy]

As discussed here: #582

Here is my first batch of additions to jakarta.ee/src/static/_headers

/specifications/platform/10/jakarta-platform-spec-10.0.html
Link: https://jakarta.ee/specifications/platform/10/jakarta-platform-spec-10.0; rel="canonical"

/specifications/platform/10/jakarta-platform-spec-10.0
Link: https://jakarta.ee/specifications/platform/10/jakarta-platform-spec-10.0; rel="canonical"

/specifications/webprofile/10/jakarta-webprofile-spec-10.0
Link: https://jakarta.ee/specifications/webprofile/10/jakarta-webprofile-spec-10.0; rel="canonical"

/specifications/webprofile/10/jakarta-webprofile-spec-10.0.html
Link: https://jakarta.ee/specifications/webprofile/10/jakarta-webprofile-spec-10.0; rel="canonical"

/specifications/coreprofile/10/jakarta-coreprofile-spec-10.0
Link: https://jakarta.ee/specifications/coreprofile/10/jakarta-coreprofile-spec-10.0; rel="canonical"

/specifications/coreprofile/10/jakarta-coreprofile-spec-10.0.html
Link: https://jakarta.ee/specifications/coreprofile/10/jakarta-coreprofile-spec-10.0; rel="canonical"

/specifications/authorization/2.1/jakarta-authorization-spec-2.1
Link: https://jakarta.ee/specifications/authorization/2.1/jakarta-authorization-spec-2.1; rel="canonical"

/specifications/authorization/2.1/jakarta-authorization-spec-2.1.html
Link: https://jakarta.ee/specifications/authorization/2.1/jakarta-authorization-spec-2.1; rel="canonical"

/specifications/batch/2.1/jakarta-batch-spec-2.1
Link: https://jakarta.ee/specifications/batch/2.1/jakarta-batch-spec-2.1; rel="canonical"

/specifications/batch/2.1/jakarta-batch-spec-2.1.html
Link: https://jakarta.ee/specifications/batch/2.1/jakarta-batch-spec-2.1; rel="canonical"

[excentrickristy]

Bumping to see if anyone can tackle this. I know it's busy pre-release.

Here is an example of Google struggling to decide what pages to serve: