MAINTAINERS: Document all stable trees

We currently host stable trees for 0.10, 0.14, 0.15 and 1.0.
Sort in descending order. It is expected that further non-stable
sections will be added above these so this order avoids scrolling
through an ever-growing list of stable trees.
Signed-off-by: NAndreas Färber <afaerber@suse.de>

MAINTAINERS

@@ -638,3 +638,25 @@ TCI target
 M: Stefan Weil <sw@weilnetz.de>
 S: Maintained
 F: tcg/tci/
+
+Stable branches
+---------------
+Stable 1.0
+L: qemu-stable@nongnu.org
+T: git git://git.qemu.org/qemu-stable-1.0.git
+S: Orphan
+
+Stable 0.15
+L: qemu-stable@nongnu.org
+T: git git://git.qemu.org/qemu-stable-0.15.git
+S: Orphan
+
+Stable 0.14
+L: qemu-stable@nongnu.org
+T: git git://git.qemu.org/qemu-stable-0.14.git
+S: Orphan
+
+Stable 0.10
+L: qemu-stable@nongnu.org
+T: git git://git.qemu.org/qemu-stable-0.10.git
+S: Orphan