[3.6] Fix typos in multiple `.rst` files (GH-1668) (#1702)

(cherry picked from commit 3378b2062c7fbb77a9b5e6d315d6b94160fac69a)
diff --git a/Doc/library/exceptions.rst b/Doc/library/exceptions.rst
index a428f51..a6b20a5 100644
--- a/Doc/library/exceptions.rst
+++ b/Doc/library/exceptions.rst
@@ -243,7 +243,7 @@
 
    .. note::
 
-      It should not be used to indicate that an operater or method is not
+      It should not be used to indicate that an operator or method is not
       meant to be supported at all -- in that case either leave the operator /
       method undefined or, if a subclass, set it to :data:`None`.