Add prefix "$" for command examples

This commits adds "$" as a prefix for command examples.

Change-Id: I4ad7a65c35d401444785fbdc1a33c2fb1fe717b1

doc/source/testing.rst

@@ -24,7 +24,7 @@ independent version, you can do so with the following command:
 .. code-block:: bash
 
     # Executes tests on Python 2.7
-    tox -e py27
+    $ tox -e py27
 
 
 .. note::
@@ -53,7 +53,7 @@ run functional tests. A sample file can be generated by running:
 .. code-block:: bash
 
     # Generate a sample configuration file
-    tox -e genconfig
+    $ tox -e genconfig
 
 ``castellan/etc/castellan/castellan-functional.conf.sample`` is generated.
 It must be renamed to ``castellan-functional.conf`` and placed in
@@ -77,7 +77,7 @@ the functional tests through tox.
 .. code-block:: bash
 
     # Execute Barbican Functional Tests
-    tox -e functional
+    $ tox -e functional
 
 
 By default, the functional tox job will use ``testr`` to execute the
@@ -93,7 +93,7 @@ to set the breakpoint. Then run the following command to hit the breakpoint:
 .. code-block:: bash
 
     # hit the pdb breakpoint
-    tox -e debug
+    $ tox -e debug
 
 Once in the Python Debugger, you can use the commands as stated in the
 `Debugger Commands` section here: https://docs.python.org/2/library/pdb.html
@@ -108,6 +108,6 @@ tox as follows:
 .. code-block:: bash
 
     # Checks python code style
-    tox -e pep8
+    $ tox -e pep8
 
 Any comments on bad coding style will output to the terminal.