Update docstring for Session.verify to include string support (#6859)

Author: M0d3v1

src/requests/sessions.py

@@ -421,6 +421,8 @@ def __init__(self):
         #: presented by the server, and will ignore hostname mismatches and/or
         #: expired certificates, which will make your application vulnerable to
         #: man-in-the-middle (MitM) attacks.
+        #: If verify is set to a string, it must be the path to a CA bundle file
+        #: that will be used to verify the TLS certificate.
         #: Only set this to `False` for testing.
         self.verify = True