roll contributring info into readme

Author: daniely

CONTRIBUTING.md

@@ -130,19 +130,41 @@ See source code for examples of how to write your own reporters.
 
 * ansi 1.1+ (for colorized output and progress bar output mode)
 
-
 ## INSTALLATION
 
 Follow the ususal procedure:
 
     $ gem install turn
 
-
 ## TODO
 
 * Support MiniTest v5.0
 * General code cleanup
 
+# CONTRIBUTING
+
+1. Fork it
+2. Create your feature branch (`git checkout -b my_new_feature`)
+3. Commit your changes (`git commit -am 'Added some feature'`)
+4. Push to the branch (`git push origin my_new_feature`)
+5. Create a new Pull Request
+
+If you are a project member please follow the same process (minus the forking). For significant changes please wait for another developer to review and merge them, whereas small contributions/fixes can be merged without review.
+
+## Building
+
+`gem build turn.gemspec`
+
+## Solo and Cross Runners
+
+An important aspect of Turn's design that needs be kept in mind, is the way
+_solo_ and _cross_ testing features are implemented. This is some really
+neat code actually (IMO), but it might be difficult to grasp with out some
+explanation. What turn does when using the `--solo` or `--cross` options,
+is <i>shell out to itself</i> using the YAML reporter. It does this repeatedly
+for each test, or each pair of tests, respectively, and then collates all the
+resulting YAML reports into a single report, which it then feeds back into the
+selected reporter.
 
 ## LICENSE