[Qemu-trivial] [PATCH] hw/display/cirrus_vga: Update the documentation URL

[Philippe Mathieu-Daudé]

The documentation URL is not working, but is backed up by the
Wayback Machine on the Internet Archive.
Replace the outdated link by a captured one.
Add another link to the VGADOC4b.ZIP archive content.

Signed-off-by: Philippe Mathieu-Daudé <address@hidden>
---
 hw/display/cirrus_vga.c | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/hw/display/cirrus_vga.c b/hw/display/cirrus_vga.c
index a0e71469f4d..a04440b3748 100644
--- a/hw/display/cirrus_vga.c
+++ b/hw/display/cirrus_vga.c
@@ -23,8 +23,13 @@
  * THE SOFTWARE.
  */
 /*
- * Reference: Finn Thogersons' VGADOC4b
- *   available at http://home.worldonline.dk/~finth/
+ * Reference: Finn Thogersons' VGADOC4b:
+ *
+ *  http://web.archive.org/web/20021019054927/http://home.worldonline.dk/finth/
+ *
+ * VGADOC4b.ZIP content available at:
+ *
+ *  https://pdos.csail.mit.edu/6.828/2005/readings/hardware/vgadoc
  */
 #include "qemu/osdep.h"
 #include "qemu/units.h"
-- 
2.20.1