Update windows.md

Update Program Files path description, the default install folder is "Boot2Docker", rather than "Docker"
Minor typo/format fixes

This fixes a code block typo so it renders as a code block.  Additionally synchronizes the variable prefix examples from 'DB' and 'DB1_' to 'DB_' and 'DB1_'
Merge pull request #6568 from jokajak/patch-2

Minor typo/format fixes for dockerlinks.md
Merge pull request #6565 from shaunol/patch-1

Update windows.md