Readme: Add explanatory text, link to docs
Readme: Add explanatory text, link to docs

Mention that the software is free and runs on
the major operating systems of the day. Point to
the documentation. Clean up the installation 
markdown.
holmwell/circle-blvd,ellipsonic/circle-blvd,holmwell/circle-blvd,myersg86/circle-blvd,ellipsonic/circle-blvd,secret-project/circle-blvd,holmwell/circle-blvd,secret-project/circle-blvd,secret-project/circle-blvd,myersg86/circle-blvd,myersg86/circle-blvd,myersg86/circle-blvd,ellipsonic/circle-blvd,secret-project/circle-blvd,holmwell/circle-blvd,ellipsonic/circle-blvd