twrpme: add gitactivity changelog tag to device markdowns

Change-Id: I437a42c1b2ccd79b3f85ad0962c362680c28d171
diff --git a/_devices/xiaomimi3.markdown b/_devices/xiaomimi3.markdown
index b2b99f3..ed5ae61 100644
--- a/_devices/xiaomimi3.markdown
+++ b/_devices/xiaomimi3.markdown
@@ -6,6 +6,7 @@
 oldurl: http://teamw.in/project/twrp2/288
 supportstatus: Current
 maintainer: None
+devicetree: https://github.com/TeamWin/android_device_xiaomi_cancro.git
 oem: Xiaomi
 ---