docs: forwarder-headers is list, not mapping

gunicorn/config.py

@@ -2361,17 +2361,13 @@ class ForwarderHeaders(Setting):
     default = "SCRIPT_NAME"
     desc = """\
 
-        A list containing headers and values that the front-end proxy
+        A list containing upper-case header field names that the front-end proxy
         sets, to be used in WSGI environment.
 
-        If other headers listed in this list are not present in the request, they will be ignored.
+        If headers named in this list are not present in the request, they will be ignored.
 
         This option can be used to transfer SCRIPT_NAME and REMOTE_USER.
 
-        The list should map upper-case header names to exact string
-        values. The value comparisons are case-sensitive, unlike the header
-        names, so make sure they're exactly what your front-end proxy sends.
-
         It is important that your front-end proxy configuration ensures that
         the headers defined here can not be passed directly from the client.
         """