config: Update zonecfg(1M) link to match config-solaris.md

With the same link update that config-solaris.md got in ea65eb3
(config-solaris.md: fix info, 2017-04-28, opencontainers#786), since the old link
404s.

Signed-off-by: W. Trevor King <wking@tremily.us>

config.md

@@ -835,4 +835,4 @@ Here is a full example `config.json` for reference.
 [setrlimit.2]: http://man7.org/linux/man-pages/man2/setrlimit.2.html
 [stdin.3]: http://man7.org/linux/man-pages/man3/stdin.3.html
 [uts-namespace.7]: http://man7.org/linux/man-pages/man7/namespaces.7.html
-[zonecfg.1m]: http://docs.oracle.com/cd/E53394_01/html/E54764/zonecfg-1m.html
+[zonecfg.1m]: https://docs.oracle.com/cd/E36784_01/html/E36871/zonecfg-1m.html