Improve docstrings in offsetbox.py (matplotlib#16085)

* Improve docstrings in offsetbox.py

* Improve docstrings in offsetbox.py

Author: timhoffm

doc/api/offsetbox_api.rst

@@ -2,6 +2,9 @@
 ``matplotlib.offsetbox``
 ************************
 
+.. inheritance-diagram:: matplotlib.offsetbox
+   :parts: 1
+
 .. automodule:: matplotlib.offsetbox
    :members:
    :undoc-members:

lib/matplotlib/animation.py

@@ -1477,7 +1477,7 @@ def _loop_delay(self, *args):
 
 class ArtistAnimation(TimedAnimation):
     """
-    Animation using a fixed set of `Artist` objects.
+    Animation using a fixed set of `.Artist` objects.
 
     Before creating an instance, all plotting should have taken place
     and the relevant artists saved.

lib/matplotlib/artist.py

@@ -1217,7 +1217,7 @@ def __init__(self, o):
         r"""
         Initialize the artist inspector with an `Artist` or an iterable of
         `Artist`\s.  If an iterable is used, we assume it is a homogeneous
-        sequence (all `Artists` are of the same type) and it is your
+        sequence (all `Artist`\s are of the same type) and it is your
         responsibility to make sure this is so.
         """
         if not isinstance(o, Artist):

lib/matplotlib/legend.py

@@ -424,7 +424,7 @@ def __init__(self, parent, handles, labels,
         self._scatteryoffsets = np.tile(self._scatteryoffsets,
                                         reps)[:self.scatterpoints]
 
-        # _legend_box is an OffsetBox instance that contains all
+        # _legend_box is a VPacker instance that contains all
         # legend items and will be initialized from _init_legend_box()
         # method.
         self._legend_box = None