Make heading structure more consistent across sections

[ribose-jeffreylau]

Currently, our API doc is inconsistent in that the headings for our plural and singular resources don't follow one set of convention. E.g., for Calendar and Wiki, they use the "Resources" (plural) - "Resource" (singular) heading pair, while for other sections, well, they don't seem to follow any convention.

It would be great if they would all follow the "Resources" - "Resource" convention:

• "Resources" (plural) would contain index, create
• "Resource" (singular) would contain show, update, destroy

(See: https://developer.veeqo.com/docs#/reference/orders for ideas. They use the "Resource Collection" - "Resource" pair instead, but I think it's a matter of personal preference.)

[skalee]

I opt for longer titles, e.g. "Delete a calendar", not just "Delete", or "Deleting". It's easy to lose oneself in long documents, and it really helps then.

[ronaldtse]

Agree with @skalee -- better description the better!