Clarify get_masked_triangles and minor grammar fix

Author: oscargus

lib/matplotlib/tri/triangulation.py

@@ -104,7 +104,7 @@ def edges(self):
         Return integer array of shape (nedges, 2) containing all edges of
         non-masked triangles.
 
-        Each row defines an edge by it's start point index and end point
+        Each row defines an edge by its start point index and end point
         index.  Each edge appears only once, i.e. for an edge between points
         *i*  and *j*, there will only be either *(i, j)* or *(j, i)*.
         """
@@ -126,7 +126,7 @@ def get_cpp_triangulation(self):
 
     def get_masked_triangles(self):
         """
-        Return an array of triangles that are not masked.
+        Return an array of triangles taking the mask into account.
         """
         if self.mask is not None:
             return self.triangles[~self.mask]

lib/matplotlib/tri/tricontour.py

@@ -129,7 +129,7 @@ def _contour_args(self, args, kwargs):
     The colors of the levels, i.e., the contour %%(type)s.
 
     The sequence is cycled for the levels in ascending order. If the sequence
-    is shorter than the number of levels, it's repeated.
+    is shorter than the number of levels, it is repeated.
 
     As a shortcut, single color strings may be used in place of one-element
     lists, i.e. ``'red'`` instead of ``['red']`` to color all levels with the