Use www.coreboot.org over coreboot.org

<https://coreboot.org> is redirected to <https://www.coreboot.org>.

```
$ curl -I https://coreboot.org
HTTP/1.1 301 Moved Permanently
Server: nginx/1.8.1
Date: Mon, 05 Jun 2017 10:41:33 GMT
Content-Type: text/html
Content-Length: 184
Connection: keep-alive
Location: https://www.coreboot.org/

```

So use the command below to use the final location to save a redirect.

```
$ git grep -l https://coreboot.org \
| xargs sed -i 's,https://coreboot.org,https://www.coreboot.org,g'
```

Change-Id: I4176c20ef31399f0063b41e3a0029cca0c1b0ff3
Signed-off-by: Paul Menzel <paulepanter@users.sourceforge.net>
Reviewed-on: https://review.coreboot.org/20035
Reviewed-by: Stefan Reinauer <stefan.reinauer@coreboot.org>
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>

util/nvramtool/cli/nvramtool.8

@@ -9,7 +9,7 @@
 .\"
 .\"  This file is part of nvramtool, a utility for reading/writing coreboot
 .\"  parameters and displaying information from the coreboot table.
-.\"  For details, see https://coreboot.org/nvramtool.
+.\"  For details, see https://www.coreboot.org/nvramtool.
 .\"
 .\"  Please also read the file DISCLAIMER which is included in this software
 .\"  distribution.