Update usage.rst

Updates usage documentation to note default licence

docs/usage.rst

@@ -133,6 +133,11 @@ The ``resource_license`` is in the form of a dictionary with mandatory string ``
 The optional argument ``file_type="HistFactory"`` (default value of ``None``) can be used to identify statistical models provided in the HistFactory JSON
 format rather than relying on certain trigger words in the ``description`` (see `pyhf section of submission documentation`_).
 
+**Please note:** The default license applied to records uploaded to HEPData is `CC0`_. You do not
+need to specify a license by default.
+
+.. _`CC0`: https://creativecommons.org/public-domain/cc0/
+
 The ``add_link`` function can alternatively be used to add a link to an external resource:
 
 ::
@@ -329,6 +334,11 @@ Adding a data license
 You can add data license information to a table using the ``add_data_license`` function of the Table class.
 This function takes mandatory ``name`` and ``url`` string arguments, as well as an optional ``description``.
 
+**Please note:** The default license applied to records uploaded to HEPData is `CC0`_. You do not
+need to specify a license by default.
+
+.. _`CC0`: https://creativecommons.org/public-domain/cc0/
+
 ::
 
     table.add_data_license("CC BY 4.0", "https://creativecommons.org/licenses/by/4.0/")