[storages] Fix docstrings

cubicweb_s3storage/storages.py

@@ -137,10 +137,6 @@
         """
         Return the S3 key of the S3 object storing the content of attribute
         attr of the entity.
-
-        If the given entity already has a key (eg. at entity creation time),
-        a new  key is generated.
-
         """
         try:
             rset = entity._cw.execute(
@@ -160,7 +156,7 @@
     def new_s3_key(self, entity, attr):
         """Generate a new key for given entity attr.
 
-        This implemenation just return a random UUID"""
+        This implementation just returns a random UUID"""
         return str(uuid.uuid1())
 
     def suffixed_key(self, key):