fix(#766): include API identifiers and compatibility result in Markdown output

[ctreatma]

This updates the Markdown output so that:

• The API title and version are printed before the diff details, which makes it possible to match diff output to the input specs in cases where users might be running multiple diffs at once
• The diff result is printed after the diff details, so that Markdown output mentions whether the API specs are unchanged or backwards compatible

[ctreatma]

Is there an ETA for a new release that includes these changes? Or are there additional changes that need to be made before a new release can be cut?

[DrSatyr]

@ctreatma, let's wait for #863, and I will createa new minor release then.