support/scripts: document args to _is_package() in gen-manual-lists

Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Cc: Samuel Martin <s.martin49@gmail.com>
Acked-by: Samuel Martin <s.martin49@gmail.com>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

support/scripts/gen-manual-lists.py

@@ -242,6 +242,8 @@ class Buildroot:
         """ Return True if the symbol is a package or a host package, otherwise
         False.
 
+        :param symbol:  The symbol to check
+
         """
         if not self.re_pkg_prefix.match(symbol.get_name()):
             return False