[1.8.x] Specified file names for example code in docs/topics/forms/index.txt

Backport of f9c212d09a from master

docs/topics/forms/index.txt

@@ -224,7 +224,10 @@ The :class:`Form` class
 ^^^^^^^^^^^^^^^^^^^^^^^
 
 We already know what we want our HTML form to look like. Our starting point for
-it in Django is this::
+it in Django is this:
+
+.. snippet::
+    :filename: forms.py
 
     from django import forms
 
@@ -271,11 +274,16 @@ same view which published the form. This allows us to reuse some of the same
 logic.
 
 To handle the form we need to instantiate it in the view for the URL where we
-want it to be published::
+want it to be published:
+
+.. snippet::
+    :filename: views.py
 
     from django.shortcuts import render
     from django.http import HttpResponseRedirect
 
+    from .forms import NameForm
+
     def get_name(request):
         # if this is a POST request we need to process the form data
         if request.method == 'POST':
@@ -392,7 +400,10 @@ More on fields
 --------------
 
 Consider a more useful form than our minimal example above, which we could use
-to implement "contact me" functionality on a personal Web site::
+to implement "contact me" functionality on a personal Web site:
+
+.. snippet::
+    :filename: forms.py
 
     from django import forms
 
@@ -438,7 +449,10 @@ In the contact form example above, ``cc_myself`` will be a boolean value.
 Likewise, fields such as :class:`IntegerField` and :class:`FloatField` convert
 values to a Python ``int`` and ``float`` respectively.
 
-Here's how the form data could be processed in the view that handles this form::
+Here's how the form data could be processed in the view that handles this form:
+
+.. snippet::
+    :filename: views.py
 
     from django.core.mail import send_mail