Identify two environments:  Docker for Windows / Mac / Linux and Legacy
OS (Windows 7, 8.1, 10 Home Premium).  Provide docker run commeands for
each environment.

Close #184

Close #86

This way the docker image shows the repository that was used to generate
the image and people can go to that repo to look at the Dockerfile used.

This updates the docs to ensure that hook parameters exactly match the names
in the code.

Prior to 4.7.19, the names of hook-parameters didn't really matter (as long
as they were in the right order).  In 4.7.19, the names took on extra
significance because Symfony-based listeners use objects and fields (e.g.
`$event->firstParam`) instead of ordered params (`function($firstParam)`).

 * Rewrite "Events"
 * Use more consistent style in the two examples
 * Move some "notes" into new section, "Methods"

What's wrong with a little inversion of logic?

Updated line 627 to "For use with CiviCRM 4.3 and later," per info from @totten

Add links to other documentation, clean up grammar and formatting, clarify a couple points

I've seen a incidents where an extension developer tries to hardcode paths
(based on their knowledge/understanding of the file-structure).  This is
usually a bad idea, so I'd like to expose the programmatic way as part of
the docs.