[ruby] Add basic RVM, ruby, jruby, ree installation instructions

ruby/README.md

@@ -0,0 +1,28 @@
+Ruby
+====
+
+## RVM: ruby version manager
+
+```bash
+$ curl -L https://get.rvm.io
+$ chmod +x rvm-installer
+$ export rvm_path=$(pwd)/rvm
+$ ./rvm-installer
+$ source $(rvm_path)/scripts/rvm
+```
+
+```bash
+$ rvm list known
+```
+
+JRuby:
+
+```bash
+$ rvm install jruby-1.6.5.1
+```
+
+Ruby Enterprise Edition
+
+```bash
+$ rvm install ree
+```