documentation: Clear Sphinx warnings

doc/manual/source/python.rst

@@ -302,6 +302,8 @@ Set up a ``bake`` build environment
 
 Try the following commands::
 
+.. sourcecode:: bash
+
     $ cd bake
     $ export BAKE_HOME=`pwd`
     $ export PATH=$PATH:$BAKE_HOME/build/bin
@@ -314,15 +316,21 @@ Configure
 
 Perform a configuration at the bake level::
 
+.. sourcecode:: bash
+
     $ ./bake.py configure -e ns-3-dev -e pygccxml-1.9.1
 
 The output of ``bake show`` should show something like this: 
 ::
 
+.. sourcecode:: bash
+
     $ ./bake.py show
 
 Should say::
 
+.. sourcecode:: text
+
     -- System Dependencies --
      > clang-dev - OK
      > g++ - OK
@@ -333,12 +341,13 @@ Should say::
      > qt - OK
      > setuptools - OK
 
-
 Download
 ########
 
 Try the following command::
 
+.. sourcecode:: bash
+
     $ ./bake.py download
      >> Searching for system dependency python-dev - OK
      >> Searching for system dependency clang-dev - OK
@@ -359,6 +368,8 @@ Build
 
 Try the following commands::
 
+.. sourcecode:: text
+
     $ mkdir -p build/lib
     $ ./bake.py build
 
@@ -369,12 +380,16 @@ support is enabled:
 
 ::
 
+.. sourcecode:: text
+
   Python API Scanning Support   : enabled
 
 It may say something like this, if the support is not active:
 
 ::
 
+.. sourcecode:: text
+
   Python API Scanning Support   : not enabled (Missing 'pygccxml' Python module)
 
 In this case, the user must take steps to install castxml and pygccxml;
@@ -405,6 +420,8 @@ To re-scan a module:
 
 ::
 
+.. sourcecode:: bash
+
     $ cd source/ns-3-dev
     $ ./waf --apiscan=wifi