Merge pull request #1 from voxik/master

More descriptive README

README.md

@@ -1,6 +1,32 @@
 rubypick
 =========
 
-Fedora /usr/bin/ruby stub to allow choosing Ruby runtime.
+Fedora /usr/bin/ruby stub to allow choosing Ruby runtime. Similarly to rbenv [1] or RVM [2], it allows non-privileged user to choose which is preferred Ruby runtime for current task.
+
+The following are supported runtimes under Fedora:
+
+Ruby - binary /usr/bin/ruby-mri
+JRuby - binary /usr/bin/jruby
+
+To run a specific runtime, use:
+ruby _mri_ [params]
+ruby _jruby_ [params]
+The default is _mri_.
+
+To run Ruby executables with shebang, such as 'gem', you can also use these:
+gem _mri_ install foo
+gem _jruby_ install foo
+
+Or you can set environment variable RUBYPICK like this:
+RUBYPICK=_mri_
+RUBYPICK=_jruby_
+and then MRI, resp. JRuby will be used for all ruby invocations.
+This is still overriden by using the parameter as mentioned above.
+
+If you don't want to use rubypick, you can always fall back to
+using the above binaries.
 
 Licensed under MIT License.
+
+[1] http://rbenv.org/
+[2] https://rvm.io/