Any help to improve the documentation is welcome!
If you want to explain how to configure a specific operation in Duplicati, posting it in the #howto section of this forum is your best choice.
If you want to improve something in the manual (better explanation, fix a typo), just do a PR at Github.
If you want to add some technical information about how the software works that’s applicable to any backend, please add an article to the Articles section of the manual and do a PR.
My guess is that a step-by-step guide on how to configure SSH/SFTP and how to configure blocking tampering backend files fits best in the #howto section of the forums. There are some great documents with comparable content in that category (example).
But you’re the author ofyour files, if you think that your docs relate to general use of Duplicati (instead of a specific part, like a particular backend), feel free to submit a PR on Github!