twrpme: add gitactivity changelog tag to device markdowns

Change-Id: I437a42c1b2ccd79b3f85ad0962c362680c28d171
diff --git a/_devices/sonyxperiaz2.markdown b/_devices/sonyxperiaz2.markdown
index da21fd0..3f7904e 100644
--- a/_devices/sonyxperiaz2.markdown
+++ b/_devices/sonyxperiaz2.markdown
@@ -6,6 +6,7 @@
 oldurl: http://teamw.in/project/twrp2/232
 supportstatus: Current
 maintainer: None
+devicetree: https://github.com/TeamWin/android_device_sony_sirius.git
 oem: Sony
 ddof: /dev/block/platform/msm_sdcc.1/by-name/FOTAKernel
 ---