Get rid of vague memunits from the man page

Our man page has vague lines like

**BandwidthRate** __N__ **bytes**|**KB**|**MB**|**GB**::

and

(Default: 1 GB)

Wouldn't it be nicer if we said Bytes rather than B in each case? Then it would be the default for people to say KBytes, and just a happy coincidence that our code happens to handle the shorthand version of it too.