qemu-doc: Add hyperlinks to further license information

Add a link to the GPLv2 and a link to the LICENSE file in the
QEMU repository to fix the two TODO items in this appendix.

Signed-off-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>

qemu-doc.texi

@@ -3021,10 +3021,10 @@ Run the emulation in single step mode.
 
 QEMU is a trademark of Fabrice Bellard.
 
-QEMU is released under the GNU General Public License (TODO: add link).
-Parts of QEMU have specific licenses, see file LICENSE.
-
-TODO (refer to file LICENSE, include it, include the GPL?)
+QEMU is released under the
+@url{https://www.gnu.org/licenses/gpl-2.0.txt,GNU General Public License},
+version 2. Parts of QEMU have specific licenses, see file
+@url{http://git.qemu.org/?p=qemu.git;a=blob_plain;f=LICENSE,LICENSE}.
 
 @node Index
 @appendix Index