Adds the initial chapter on mu

Author: kushaldas

docs/img/mu_running_code.gif

@@ -19,6 +19,7 @@ Contents:
 
    installation
    thebeginning
+   mu
    variablesanddatatypes
    operatorsexpressions
    ifelse

docs/img/mu_starting.gif

@@ -0,0 +1,52 @@
+================
+Using an editor
+================
+
+Using a proper editor to write code can help a lot while programming or while
+working on actual projects. In this chapter we will learn about **mu editor**,
+which is a very simple and beginner friendly editor for anyone starting with
+Python. It is developed by Nicholas Tollervey.
+
+If you already have an editor of your choice, you can skip this chapter. 
+
+Installation
+=============
+
+The total download size is around 150MB. Means it will take some time. Give
+the following command as your normal user.
+
+::
+
+    $ python3 -m pip install -U mu-editor --user
+
+
+
+Using mu
+---------
+
+You can open the editor from the command line, type **mu** in the terminal.
+
+::
+
+    $ python3 -m mu
+
+
+.. figure:: img/mu_starting.gif
+
+
+Select Python 3 at the starting screen. Now, your mu editor is ready.
+
+
+Executing code
+--------------
+
+You will have to write any code you want to execute, and then save it with a
+proper filename (ends with .py). Then click on the **Run** button to execute
+the code. If you want a REPL, then click on the **REPL** button.
+
+.. note:: Remember not to give any space in the filename. Use _ if required, example: download_photos.py
+
+.. figure:: img/mu_running_code.gif
+
+
+