Add tldr for rails command.

pages/common/rails.md

@@ -0,0 +1,23 @@
+# rails
+
+> Ruby on Rails, or Rails, is a server-side MVC framework written in Ruby under the MIT License.
+
+- Check current version of rails:
+
+`rails --version`
+
+- Create a new rails project:
+
+`rails new "{{name_of_project}}"`
+
+- Start local server for current project on port 3000 (while in projects root directory):
+
+`rails server`
+
+- Start local server for current project on a specified port:
+
+`rails server -p "{{port_number}}"`
+
+- Open console to interact with applicaiton from command line (while in projects root directory):
+
+`rails console`