reST formatting errors in PseudoPositioner

[prjemian]

When building Sphinx docs for a new package including the ophyd PseudoPositioner, Sphinx raises this exception:

path/to/project/file.py:docstring of ophyd.pseudopos.PseudoPositioner._get_real_positioners:3: WARNING: Inline interpreted text or phrase reference start-string without end-string.

[prjemian]

In this line:

ophyd/ophyd/pseudopos.py

Line 548 in 5c03c3f

All `Positioner` components which are not `PseudoSingle`s will be

the intent is to show Positioner and PseudoSingle as computer code. The correct reST syntax is to use two back-ticks when enclosing such text. The root cause of the problem, though, is rendering the term "PseudoSingles". This cannot be rendered in reST (maybe it could be but it is not an easy task).

Local editing shows that this rewrite will not raise the error:

        All ``Positioner`` components which are not ``PseudoSingle`` objects will be