Merge 54a394c into 640c8d8

docs/usage.rst

@@ -3,9 +3,18 @@ Usage
 =====
 
 Particles are a key component when dealing with decays.
-Refer to the [particle package](https://github.com/scikit-hep/particle) for how to deal with particles and PDG identification codes.
+Refer to the `particle package`_ for how to deal with particles and PDG identification codes.
 
-The primary way to use `decaylanguage.decay` is through the module provided to read in a language file and produce an output. For example, for GooFit, call:
+
+DecFiles
+--------
+
+DecFiles describe decays. You can read files and query information about them.
+
+DecayLanguage
+-------------
+
+The primary way to use ``decaylanguage.decay`` is through the module provided to read in a language file and produce an output. For example, for GooFit, call:
 
 .. code-block:: bash
 
@@ -14,3 +23,5 @@ The primary way to use `decaylanguage.decay` is through the module provided to r
 You can pipe the output to a file.
 
 Examples of interaction with the API directly are provided in the ``/notebooks`` folder, including svg diagrams of lines.
+
+.. particle package: https://github.com/scikit-hep/particle