docs: fix table of contents links

[Ascenio]

New Pull Request Checklist

• I have read the Documentation
• I have searched for a similar pull request in the project and found none
• I have updated this branch with the latest develop to avoid conflicts (via merge from master or rebase)
• I have added the required tests to prove the fix/feature I am adding
• I have updated the documentation (if necessary)
• I have run the tests and they pass

Pull Request Description

This PR fixes the table of contents by updating both Transformer and Using proxy's URLs.
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[kuhnroyal]

Thanks!