add definitions box

Author: jennyhickson

source/WorkingPractices/branches.rst

@@ -59,14 +59,24 @@ the process is very comparable to that of the other repositories too.
 
     To get started with the ``gh`` cli, see the `gh quickstart guide <https://docs.github.com/en/github-cli/github-cli/quickstart>`_
 
+.. admonition:: Definitions
+
+    ``Upstream``: the primary or parent repository, owned by the MetOffice github organisation. Only maintainers have write access to this repository.
+
+    ``Fork`` or ``Downstream``: a copy of the upstream repository, owned by the developer. This is where development branches are created and worked on.
+
+    ``Remote``: the version of the upstream or forked repository that is hosted by Github.
+
+    ``Clone``: a local copy of the upstream or forked repository.
+
 Simulation Systems github repositories are setup with at least 2 protected branches, ``stable`` and ``main`` (with the potential for additional version branches to be added).
 
 * ``stable`` - This branch is the default github branch and generally remains unchanged throughout a release cycle. It is the stable point from which new branches should be cut. Only new releases and small hotfixes to a release will be merged back into this branch.
 * ``main`` - This branch is where new development pull requests will be merged. It will never be behind the ``stable`` branch, but will regularly be ahead. All pull requests should be set to target this branch (more on this later) and a CI check will fail if it isn't. 
 
-All general development for Simulation Systems Github repos will take place on forks of that repository. It is the responsibility of the developer to maintain their own fork. See :ref:`forking` for advice on forking.
+All general development for Simulation Systems Github repositories will take place on forks of that repository. It is the responsibility of the developer to maintain their own fork. See :ref:`forking` for advice on forking.
 
-The development cycle can be seen below. ``Upstream`` (blue) refers to parent repository, owned by the MetOffice github organisation. ``Downstream`` (grey) refers to the forked repository, owned by the developer.
+The development cycle can be seen below.
 
 .. image:: images/git-dev-strategy.svg
     :class: dark-light