[1.10.x] Updated "fork Django on GitHub" link.

Backport of b741fe397a from master

docs/internals/contributing/writing-code/unit-tests.txt

@@ -21,8 +21,7 @@ Running the unit tests
 Quickstart
 ----------
 
-First, `fork Django on GitHub
-<https://github.com/django/django#fork-destination-box>`__.
+First, `fork Django on GitHub <https://github.com/django/django/fork>`__.
 
 Second, create and activate a virtual environment. If you're not familiar with
 how to do that, read our :doc:`contributing tutorial </intro/contributing>`.

docs/internals/contributing/writing-code/working-with-git.txt

@@ -42,7 +42,8 @@ Setting up local repository
 ===========================
 
 When you have created your GitHub account, with the nick "GitHub_nick", and
-forked Django's repository, create a local copy of your fork::
+`forked Django's repository <https://github.com/django/django/fork>`__,
+create a local copy of your fork::
 
     git clone git@github.com:GitHub_nick/django.git
 

docs/intro/contributing.txt

@@ -111,9 +111,9 @@ Getting a copy of Django's development version
 ==============================================
 
 The first step to contributing to Django is to get a copy of the source code.
-First, `fork Django on GitHub <https://github.com/django/django#fork-destination-box>`__.
-Then, from the command line, use the ``cd`` command to navigate to the
-directory where you'll want your local copy of Django to live.
+First, `fork Django on GitHub <https://github.com/django/django/fork>`__. Then,
+from the command line, use the ``cd`` command to navigate to the directory
+where you'll want your local copy of Django to live.
 
 Download the Django source code repository using the following command: