diff --git a/CONTRIBUTING.rst b/CONTRIBUTING.rst
index 2c44422a0..94dc65048 100644
--- a/CONTRIBUTING.rst
+++ b/CONTRIBUTING.rst
@@ -30,11 +30,10 @@ use github's pull request workflow to review the contribution, and either ask
 you to make any refinements needed or merge it and make them ourselves. The
 changes will then land on master when we next do a release.
 
-We use `CircleCI <https://circleci.com/gh/matrix-org>`_ and `Buildkite
-<https://buildkite.com/matrix-dot-org/synapse>`_ for continuous integration.
-Buildkite builds need to be authorised by a maintainer. If your change breaks
-the build, this will be shown in GitHub, so please keep an eye on the pull
-request for feedback.
+We use `Buildkite <https://buildkite.com/matrix-dot-org/synapse>`_ for
+continuous integration.  Buildkite builds need to be authorised by a
+maintainer. If your change breaks the build, this will be shown in GitHub, so
+please keep an eye on the pull request for feedback.
 
 To run unit tests in a local development environment, you can use:
 
@@ -70,13 +69,21 @@ All changes, even minor ones, need a corresponding changelog / newsfragment
 entry. These are managed by Towncrier
 (https://github.com/hawkowl/towncrier).
 
-To create a changelog entry, make a new file in the ``changelog.d``
-file named in the format of ``PRnumber.type``. The type can be
-one of ``feature``, ``bugfix``, ``removal`` (also used for
-deprecations), or ``misc`` (for internal-only changes).
+To create a changelog entry, make a new file in the ``changelog.d`` file named
+in the format of ``PRnumber.type``. The type can be one of the following:
 
-The content of the file is your changelog entry, which can contain Markdown
-formatting. The entry should end with a full stop ('.') for consistency.
+* ``feature``.
+* ``bugfix``.
+* ``docker`` (for updates to the Docker image).
+* ``doc`` (for updates to the documentation).
+* ``removal`` (also used for deprecations).
+* ``misc`` (for internal-only changes).
+
+The content of the file is your changelog entry, which should be a short
+description of your change in the same style as the rest of our `changelog
+<https://github.com/matrix-org/synapse/blob/master/CHANGES.md>`_. The file can
+contain Markdown formatting, and should end with a full stop ('.') for
+consistency.
 
 Adding credits to the changelog is encouraged, we value your
 contributions and would like to have you shouted out in the release notes!
diff --git a/changelog.d/5619.docker b/changelog.d/5619.docker
new file mode 100644
index 000000000..b69e5cc57
--- /dev/null
+++ b/changelog.d/5619.docker
@@ -0,0 +1 @@
+Base Docker image on a newer Alpine Linux version (3.8 -> 3.10).
diff --git a/changelog.d/5619.misc b/changelog.d/5619.misc
deleted file mode 100644
index c5e22d205..000000000
--- a/changelog.d/5619.misc
+++ /dev/null
@@ -1 +0,0 @@
-Base Docker image on a newer Alpine Linux version (3.8 -> 3.10)
diff --git a/changelog.d/5620.bugfix b/changelog.d/5620.docker
similarity index 80%
rename from changelog.d/5620.bugfix
rename to changelog.d/5620.docker
index 17e1f133e..cbb5a75d6 100644
--- a/changelog.d/5620.bugfix
+++ b/changelog.d/5620.docker
@@ -1 +1 @@
-Add missing space in default logging file format generated by the Docker image
+Add missing space in default logging file format generated by the Docker image.
diff --git a/changelog.d/5655.doc b/changelog.d/5655.misc
similarity index 100%
rename from changelog.d/5655.doc
rename to changelog.d/5655.misc
diff --git a/changelog.d/5673.misc b/changelog.d/5673.misc
new file mode 100644
index 000000000..194225635
--- /dev/null
+++ b/changelog.d/5673.misc
@@ -0,0 +1 @@
+Add a `docker` type to the towncrier configuration.
diff --git a/pyproject.toml b/pyproject.toml
index ef329aab4..db4a2e41e 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -14,6 +14,11 @@
         name = "Bugfixes"
         showcontent = true
 
+    [[tool.towncrier.type]]
+        directory = "docker"
+        name = "Updates to the Docker image"
+        showcontent = true
+
     [[tool.towncrier.type]]
         directory = "doc"
         name = "Improved Documentation"