Update src/github3/repos/comparison.py

Accepting sigmavirus suggestion

Co-authored-by: Ian Stapleton Cordasco <graffatcolmingov@gmail.com>

Author: amaccormack-lumira

src/github3/repos/comparison.py

@@ -30,7 +30,10 @@ class Comparison(models.GitHubCore):
         
 
         A list of :class:`~github3.repos.commit.ShortCommit` objects
-        representing the first commits in the comparison.
+        representing up to the first 250 commits in the comparison.
+
+        If a comparison has more than 250 commits, use the commits function
+        to iterate over all available commits.
 
     .. attribute:: diff_url