The table of contents (the list at left) for the interface section of the documentation is arranged in the same order as the main tabs are in messiah, though from top to bottom instead of from left to right (plus a very important Basic Interface Info section).  Within those main tabs, any sub-tabs (such as in Setup) are also arranged as they are in messiah (but top to bottom).  However, the individual headings within there are alphabetical, based on the name of the block.  (The only exceptions are the Settings and Output sub-tabs in Render, because there are only a few blocks on those and it made more sense to list them from top to bottom, as they are on the interface.)

So if you have a question about a button or setting, just look at what the name of the block is and look at what main tab you are on.  Go to that tab in the documentation then go to the specific block.  Please note that some blocks, such as Spline and Camera, exist on several main tabs.  In cases like that, you can access the information from each area, but the pages themselves are the same.  The image of the tabs on top of each page in this section will show you what main tab (or tabs) the block is on.

One more thing:  The documentation refers to "blocks," but messiah can be set to use tabs for everything instead.  Since that is not the default though, and since the blocks way makes everything easier for documenting (and finding), that's the way we are doing it here.  Just keep that in mind if you are using tabs.  Likewise, many of these pages refer to keyboard shortcuts.  But since you can modify the shortcuts they might not be applicable to your system.  Check your Key Command Manager (on the Customize tab) to see what your settings are.