Docs: update list of supported streams in Freshdesk

[juweins]

What

The current documentation for Freshdesk source does not list all sources.

How

Added the missing entries as listed in issue #19890.
Closes #19890

🚨 User Impact 🚨

Minor.

Pre-merge Checklist

Expand the relevant checklist and delete the others.

Updating a Documentation

### Community member or Airbyter

• Grant edit access to maintainers (instructions)
• Documentation updated
• PR name follows PR naming conventions

Airbyter

If this is a community PR, the Airbyte engineer reviewing this PR is responsible for the below items.

• Create a non-forked branch based on this PR and test the below items on it
• Build is successful
• If new credentials are required for use in CI, add them to GSM. Instructions.
• /test connector=connectors/<name> command is passing
• New Connector version released on Dockerhub and connector version bumped by running the /publish command described here

API Documentation

• Issue acceptance criteria met
• PR name follows PR naming conventions
• Documentation which references the generator is updated as needed

Tests

Manually tested all references in VSCode preview mode.