I thought the hyphenated form was current when I used it in 0d8da61e
(README.md: Add local maintainer listing, 2015-04-15, #2), but GitHub
no longer recognizes the hyphenated form.  The un-hyphenated form
seems to date back to 2012-03-06 [1], so maybe I was just confused ;).
Anyhow, fixing to use the current username.

[1]: https://github.com/rgaiacs

This is the new plan [1], instead of referring to a central listing
from CONTRIBUTING.md.

[1]: https://github.com/swcarpentry/lesson-template/issues/195#issuecomment-89643048

1.  Explaining how to use GitHub import instead of creating a repository manually.
2.  Explaining the difference between `lesson-template` and `lesson-example`.

what it's for and how to edit it for each lesson.

Actually add requirements to file

Add info to README.md

1.  Moving the build steps up to the top of `README.md`.
2.  Removed the misleading target to run the checking tool (since the tool doesn't actually work).