Replaced "trunk" with "master branch" in docs.

docs/intro/contributing.txt

@@ -213,9 +213,9 @@ we'll rewind Django's version history in git to before that ticket's patch was
 applied. This will allow us to go through all of the steps involved in writing
 that patch from scratch, including running Django's test suite.
 
-**Keep in mind that while we'll be using an older revision of Django's trunk
-for the purposes of the tutorial below, you should always use the current
-development revision of Django when working on your own patch for a ticket!**
+**Keep in mind that while we'll be using an older revision of Django for this
+tutorial, you should always use the current version of the master branch when
+working on your own patch for a ticket!**
 
 .. note::
 
@@ -292,8 +292,8 @@ errors make sure you've followed all of the previous steps properly. See
 related to deprecation warnings that you can ignore. These failures have since
 been fixed in Django.
 
-Note that the latest Django trunk may not always be stable. When developing
-against trunk, you can check `Django's continuous integration builds`__ to
+Note that the latest Django master may not always be stable. When developing
+against master, you can check `Django's continuous integration builds`__ to
 determine if the failures are specific to your machine or if they are also
 present in Django's official builds. If you click to view a particular build,
 you can view the "Configuration Matrix" which shows failures broken down by

docs/intro/whatsnext.txt

@@ -116,8 +116,8 @@ https://docs.djangoproject.com/en/dev/. These HTML pages are generated
 automatically from the text files in source control. That means they reflect the
 "latest and greatest" in Django -- they include the very latest corrections and
 additions, and they discuss the latest Django features, which may only be
-available to users of the Django development version. (See "Differences between
-versions" below.)
+available to users of the Django development version. (See
+:ref:`differences-between-doc-versions` below.)
 
 We encourage you to help improve the docs by submitting changes, corrections and
 suggestions in the `ticket system`_. The Django developers actively monitor the
@@ -137,11 +137,11 @@ In plain text
 For offline reading, or just for convenience, you can read the Django
 documentation in plain text.
 
-If you're using an official release of Django, note that the zipped package
-(tarball) of the code includes a ``docs/`` directory, which contains all the
-documentation for that release.
+If you're using an official release of Django, the zipped package (tarball) of
+the code includes a ``docs/`` directory, which contains all the documentation
+for that release.
 
-If you're using the development version of Django (aka "trunk"), note that the
+If you're using the development version of Django (aka the master branch), the
 ``docs/`` directory contains all of the documentation. You can update your
 Git checkout to get the latest changes.
 
@@ -194,26 +194,24 @@ __ https://www.gnu.org/software/make/
 Differences between versions
 ============================
 
-As previously mentioned, the text documentation in our Git repository
-contains the "latest and greatest" changes and additions. These changes often
-include documentation of new features added in the Django development version
--- the Git ("trunk") version of Django. For that reason, it's worth
-pointing out our policy on keeping straight the documentation for various
-versions of the framework.
+The text documentation in the master branch of the Git repository contains the
+"latest and greatest" changes and additions. These changes include
+documentation of new features targeted for Django's next :term:`feature
+release`. For that reason, it's worth pointing out our policy to highlight
+recent changes and additions to Django.
 
 We follow this policy:
 
-* The primary documentation on djangoproject.com is an HTML version of the
-  latest docs in Git. These docs always correspond to the latest
-  official Django release, plus whatever features we've added/changed in
-  the framework *since* the latest release.
+* The development documentation at https://docs.djangoproject.com/en/dev/ is
+  from the master branch. These docs correspond to the latest feature release,
+  plus whatever features have been added/changed in the framework since then.
 
-* As we add features to Django's development version, we try to update the
+* As we add features to Django's development version, we update the
   documentation in the same Git commit transaction.
 
 * To distinguish feature changes/additions in the docs, we use the phrase:
-  "New in version X.Y", being X.Y the next release version (hence, the one
-  being developed).
+  "New in Django Development version" for the version of Django that hasn't
+  been released yet, or "New in version X.Y" for released versions.
 
 * Documentation fixes and improvements may be backported to the last release
   branch, at the discretion of the committer, however, once a version of
@@ -221,7 +219,7 @@ We follow this policy:
   version of the docs won't get any further updates.
 
 * The `main documentation Web page`_ includes links to documentation for
-  all previous versions. Be sure you are using the version of the docs
+  previous versions. Be sure you are using the version of the docs
   corresponding to the version of Django you are using!
 
 .. _main documentation Web page: https://docs.djangoproject.com/en/dev/