Description of problem:

From this slack thread, a customer reported that the @backstage/events-backend plugin comes pre-installed with Red Hat Developer Hub (RHDH) but is not listed in the documentation under the pre-installed plugins.

Therefore, update the documentation to accurately reflect that the @backstage/events-backend plugin is included as part of the pre-installed RHDH plugins.

Steps to Reproduce

1. Verify that the @backstage/events-backend plugin is indeed pre-installed in RHDH.

2. Update the list of pre-installed plugins to include it.

3. Ensure consistency across all related documentation (for example, plugin reference lists or installation sections).

Actual results:

This discrepancy caused confusion during setup, leading to an error that was difficult to troubleshoot.

Expected results:
The documentation accurately lists the @backstage/events-backend plugin as one of the pre-installed plugins in Red Hat Developer Hub (RHDH).