Consistent example captions

[zimeon]

At the moment the document is not consistent with the formatting or labeling of examples. Common labels have the form:

• #### FULL EXAMPLE for Change Set:
• #### FULL EXAMPLE for Entity Patch
• #### EXAMPLE Entity Change Activity for Create sometimes followed with "Complete example"
• EXAMPLE Entity Change Activity for Update (not a heading)

[zimeon]

I'm not convinced that all-caps EXAMPLE is very helpful or pretty, I think we should consistently use level 4 headings, and I think it is useful to indicate whether an example is a complete JSON document or a snippet.

I propose the following two forms:

• #### Complete example of X Y Z
• #### Example excerpt of X Y Z

[zimeon]

I think this was fixed in #109 but will leave for later checks/corrections