Added Next Steps copy to Win, Mac, and Linux subsections
New opener copy; also went a little easier on Windows
Updated sample directory listing to match revised /learn/ structure
Match example input to copy in running text
Copy fixes and example corrections
Copy fixes and attempts at clarification
Cleaned up the copy and fixed introductory text a bit
Copy fixes, filling out some examples
Added step about running git-log
Filled out the instructions for pushing
Added copy to basically empty pages on pull requests and revision
Added copy on changing file names in Git
Copy for some of the empty, advanced-topics pages