Issue #26462: Doc: avoid literal_block warnings, fix syntax highlighting.

Patch by Julien Palard.
diff --git a/Doc/faq/extending.rst b/Doc/faq/extending.rst
index e78da55..c380645 100644
--- a/Doc/faq/extending.rst
+++ b/Doc/faq/extending.rst
@@ -156,6 +156,8 @@
 
 Sample code and use for catching stdout:
 
+.. code-block:: pycon
+
    >>> class StdoutCatcher:
    ...     def __init__(self):
    ...         self.data = ''
@@ -219,11 +221,15 @@
 When using GDB with dynamically loaded extensions, you can't set a breakpoint in
 your extension until your extension is loaded.
 
-In your ``.gdbinit`` file (or interactively), add the command::
+In your ``.gdbinit`` file (or interactively), add the command:
+
+.. code-block:: none
 
    br _PyImport_LoadDynamicModule
 
-Then, when you run GDB::
+Then, when you run GDB:
+
+.. code-block:: shell-session
 
    $ gdb /local/bin/python
    gdb) run myscript.py
@@ -469,6 +475,8 @@
 You can check the size of the Unicode character a Python interpreter is using by
 checking the value of sys.maxunicode:
 
+.. code-block:: pycon
+
    >>> import sys
    >>> if sys.maxunicode > 65535:
    ...     print 'UCS4 build'