Tidying webclient plugin page (rebased onto dev_5_0) (rebased onto develop)



This is the same as gh-625 but rebased onto develop.

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This is the same as gh-624 but rebased onto dev_5_0.

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This page mostly needs tidying on the 5 branches as Douglas has added a section but I figured I may as well do dev_4_4 while I was at it. Mostly whitespace and mark-up fixes.