When viewing the docs online at Readthedocs, or similar it might be
immediately apparent what version of the documentation is being
displayed. Display the version on the first line before the table of
contents to make it clear.
Moved devguide dir into userguide dir.
Since the devguide is now incorporated as the last chapter of the
userguide, removed build and configuration files from the devguide
dir, as these are no longer needed.
Task #4909
* All sections up to 2 levels deep are now shown regardless of whether they are a separate page
* Rename Xbits and Thresholding for more consistent naming
* Minor adjustment in the Payload Keywords section