DOC: Spelling + grammar in chainmap_impl.py (#17548)

Author: Giftlin

pandas/compat/chainmap_impl.py

@@ -34,10 +34,10 @@ def wrapper(self):
 
 class ChainMap(MutableMapping):
     """ A ChainMap groups multiple dicts (or other mappings) together
-    to create a single, updateable view.
+    to create a single, updatable view.
 
     The underlying mappings are stored in a list.  That list is public and can
-    accessed or updated using the *maps* attribute.  There is no other state.
+    be accessed / updated using the *maps* attribute.  There is no other state.
 
     Lookups search the underlying mappings successively until a key is found.
     In contrast, writes, updates, and deletions only operate on the first