minor: small doc improvement

docs/guide.rst

@@ -9,7 +9,7 @@ through common data structures and joining results. Although
 it's recommended to choose your own strategies, deepmerge does
 provided some preconfigured mergers for a common situations:
 
-* deepmerge.always_merger: always try to merge. in the case of mismatches, the value from the second object overrides the first o ne.
+* deepmerge.always_merger: always try to merge. in the case of mismatches, the value from the second object overrides the first one.
 * deepmerge.merge_or_raise: try to merge, raise an exception if an unmergable situation is encountered.
 * deepmerge.conservative_merger: similar to always_merger, but in the case of a conflict, use the existing value.
 
@@ -43,6 +43,8 @@ This is intentional, as an implicit copy would result in a significant performan
     result = deepcopy(base)
     always_merger.merge(result, next)
 
+    assert id(result) != id(base)
+
 Authoring your own Mergers
 ==========================
 

docs/index.rst

@@ -34,6 +34,8 @@ Example
 
     assert expected_result == result
 
+    # The merge action will change the first dict (base).
+    assert id(base) == id(result)
 
 **Custom Strategy**