[PR Workflow] Make "getting help" support information easily discoverable by specs PR authors

When a PR is submitted to specs repos, the PR author should have easy time finding information where to reach out for help if all the provided TSGs and other docs will prove unhelpful.

One way we are considering addressing it is to:

1. provide the relevant information at https://aka.ms/azsdk/support/spectools
2. ensure that aka.ms URL is discoverable, by adding it to the PR GH comment template as well as to all "details" pages of all tool failure reports, like LintDiff, Breaking Change, etc.

This PR is adding the aka.ms URL to the PR GH comment template for ARM:
- https://github.com/Azure/azure-rest-api-specs/pull/24227

For details and additional criteria, see email thread `RE: About Spec PR review requirements` from 6/2/2023.

Note this work may be in large part subsumed by:
- #6617

### Update 6/14/2023 (suppressions doc)

While updating the validation failure reports, we should also review the output to ensure it always links to suppression guidance when appropriate. This was originally mentioned by @rkmanda here:
- https://github.com/Azure/azure-rest-api-specs/pull/24227#issuecomment-1570637726

Note this guidance may need to be added to the validation reports and/or `comment.yml`:
- https://github.com/Azure/azure-sdk-tools/issues/6346

## Related work
- https://github.com/Azure/azure-sdk-tools/issues/6617