Include an 'extra_requires' for bcrypt

docs/topics/auth/passwords.txt

@@ -76,9 +76,9 @@ use it Django supports bcrypt with minimal effort.
 
 To use Bcrypt as your default storage algorithm, do the following:
 
-1. Install the `bcrypt library`_ (probably by running ``sudo pip install
+1. Install the `bcrypt library`_. This can be done by running ``pip install
-   bcrypt``, or downloading the library and installing it with ``python
+   django[bcrypt]``, or by downloading the library and installing it with
-   setup.py install``).
+   ``python setup.py install``).
 
 2. Modify :setting:`PASSWORD_HASHERS` to list ``BCryptSHA256PasswordHasher``
    first. That is, in your settings file, you'd put::

setup.py

@@ -47,6 +47,9 @@ setup(
     entry_points={'console_scripts': [
         'django-admin = django.core.management:execute_from_command_line',
     ]},
+    extras_require={
+        "bcrypt": ["bcrypt"],
+    },
     zip_safe=False,
     classifiers=[
         'Development Status :: 3 - Alpha',