Its pretty tricky to find the MMS manual unless you know where you are looking.
Its listed on the main docs.mongodb.org page, but only on the initial landing page. If you are within the documentation its tricky to find. Even if you go to the support page from MMS itself, there is only a small link that says "or read the docs" (although granted, the search bar takes you to the docs).
I think it should be easier and more visible to find the MMS docs, perhaps by allowing a "drop down" list of manuals to read from in the nav bar?