ADD: a new wiki folder for the GitHub wiki pages

git-svn-id: https://php-sql-parser.googlecode.com/svn/trunk@1244 44dcfd11-89b7-3d55-2063-5c365055f77f
Update README.md

CHG: Some hyper-links have been changed.
ADD: a submodule for the GitHub wiki
Merge branch 'svnsync'