Add notes about when warnings are issued, closes #133

Author: jpmckinney

docs/cli/ocds.rst

@@ -240,6 +240,10 @@ If you need to create a single package that is too large to hold in your system'
 
 For the Python API, see :meth:`ocdskit.combine.combine_record_packages`.
 
+.. note::
+
+   A warning is issued if a package's ``"records"`` field isn't set.
+
 combine-release-packages
 ------------------------
 
@@ -266,6 +270,10 @@ If you need to create a single package that is too large to hold in your system'
 
 For the Python API, see :meth:`ocdskit.combine.combine_release_packages`.
 
+.. note::
+
+   A warning is issued if a package's ``"releases"`` field isn't set.
+
 .. _split-record-packages:
 
 split-record-packages