fix doc formatting

docs/source/usage.rst

@@ -25,18 +25,23 @@ Experiment names and metadata
 -----------------------------
 
 The *laboratory* contains the following subdirectories:
+
 * ``work``, which is where the model is run. This contains a temporary directory
 for each experiment which is removed after a successful run.
-* ``archive``, which is where the output of completed runs is stored for each 
-experiment. 
+
+* ``archive``, which contains the output of completed runs for each 
+experiment.
 
 An experiment name is used identify the experiment inside the ``work`` and 
 ``archive`` sub-directories. This is stored in a metadata file, 
 ``metadata.yaml``, in the *control directory*. 
 The experiment name and a UUID, to uniquely identify the experiment, 
 is set in ``metadata.yaml`` when:
+
 * Using payu to clone a pre-existing git_ repository of the *control directory*
+
 * Using payu to create and checkout a new git branch in the *control directory*
+
 * Or, it is set automatically when setting up an experiment run if there is 
 not a pre-existing metadata file.
 
@@ -47,10 +52,13 @@ git branches and ensure uniqueness in shared archives, the branch name and
 a short version of the experiment UUID are added to new experiment names. 
 For example, given a control directory named ``my_expt`` and a UUID of 
 ``9fAsTc4sNYsH2ZBQGYK9TG``, the experiment name would be:
+
 * ``my_expt-perturb-9fAsT`` - if running an experiment on a branch named 
 ``perturb``.
+
 * ``my_expt-9fAsT`` - if the control directory was not a git repository or 
 running experiments from the ``main`` or ``master`` branch.
+
 * or ``my_expt`` - if running an older experiment that has a pre-existing 
 archive.