Doc: edit macros documentation

Edit to use standard wording.
Use \a commands for attributes.

Change-Id: I90262bc12fe601df81c33a9a49cc8d0e8005407e
Reviewed-by: Eike Ziller <eike.ziller@digia.com>
Doc: edit find plugin API docs

Edit for grammar and style. Remove \brief commands from
function descriptions.

Change-Id: I1f8c861f2f202f0af9056d639d6807b68ac517a2
Reviewed-by: Eike Ziller <eike.ziller@digia.com>