Fix Sphinx nitpicks fron message_ix docs (#506)

RELEASE_NOTES.rst

@@ -5,9 +5,9 @@ Migration notes
 ---------------
 Update code that imports from the following modules:
 
-- :py:`ixmp.reporting` → use :py:`ixmp.report`.
-- :py:`ixmp.reporting.computations` → use :py:`ixmp.report.operator`.
-- :py:`ixmp.utils` → use :py:`ixmp.util`.
+- :py:`ixmp.reporting` → use :mod:`ixmp.report`.
+- :py:`ixmp.reporting.computations` → use :mod:`ixmp.report.operator`.
+- :py:`ixmp.utils` → use :mod:`ixmp.util`.
 
 Code that imports from the old locations will continue to work, but will raise :class:`DeprecationWarning`.
 

ixmp/backend/__init__.py

@@ -54,7 +54,7 @@
 
 
 class ItemType(IntFlag):
-    """Type of data items in :class:`.TimeSeries` and :class:`.Scenario`."""
+    """Type of data items in :class:`.ixmp.TimeSeries` and :class:`.ixmp.Scenario`."""
 
     # NB the docstring comments ('#:') are placed as they are to ensure the
     #    output is readable.

ixmp/core/timeseries.py

@@ -277,7 +277,7 @@ def url(self) -> str:
         Examples
         --------
         To form a complete URL (e.g. to use with :meth:`.from_url`), use a configured
-        :class:`Platform` name:
+        :class:`.ixmp.Platform` name:
 
         >>> platform_name = "my-ixmp-platform"
         >>> mp = Platform(platform_name)

ixmp/report/operator.py

@@ -150,7 +150,7 @@ def data_for_quantity(
 
 
 def from_url(url: str, cls=TimeSeries) -> "TimeSeries":
-    """Return a :class:`.TimeSeries` or subclass instance, given its `url`.
+    """Return a :class:`.ixmp.TimeSeries` or subclass instance, given its `url`.
 
     Parameters
     ----------