Move Activity comment to Request body payload

The `Parameters` keyword defines URI Parameters:
https://github.com/apiaryio/api-blueprint/blob/master/API%20Blueprint%20Specification.md#def-uriparameters-section
(these should match the URI Template)

POST data should be specified in the Request section.

Signed-off-by: Alex Coles <alex@alexbcoles.com>
Merge pull request #4 from opf/feature/13954_add_edit_quote_comments_in_wp_overview