Remove Commit._deserialize doc for param_from_rev_list

The git.objects.commit.Commit._deserialize method stopped accepting
a param_from_rev_list argument in ae5a69f, but the documentation
for that parameter was never removed.

Because that was the only part of the method's docstring, and it is
a nonpublic method, and the associated _serialize method does not
have a docstring, this change simply removes the _deserialize
method's docstring without adding anything.

Author: EliahKagan

git/objects/commit.py

@@ -688,10 +688,6 @@ def _serialize(self, stream: BytesIO) -> "Commit":
         return self
 
     def _deserialize(self, stream: BytesIO) -> "Commit":
-        """
-        :param from_rev_list: if true, the stream format is coming from the rev-list command
-            Otherwise it is assumed to be a plain data stream from our object
-        """
         readline = stream.readline
         self.tree = Tree(self.repo, hex_to_bin(readline().split()[1]), Tree.tree_id << 12, "")