findmissing: Update stable branches

v5.11 is the most recent upstream kernel. Add it to the stable
branch list.

BUG=None
TEST=Run robot tools

Change-Id: Iec5f0d9b6ce4dd56bd3ce0d371a47d4717a34ce5
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/dev-util/+/2752727
Tested-by: Guenter Roeck <groeck@chromium.org>
Auto-Submit: Guenter Roeck <groeck@chromium.org>
Reviewed-by: Curtis Malainey <cujomalainey@chromium.org>
Commit-Queue: Curtis Malainey <cujomalainey@chromium.org>
diff --git a/contrib/findmissing/common.py b/contrib/findmissing/common.py
index 4c38358..2fba9bb 100755
--- a/contrib/findmissing/common.py
+++ b/contrib/findmissing/common.py
@@ -33,7 +33,7 @@
 
 # Order BRANCHES from oldest to newest
 CHROMEOS_BRANCHES = ['4.4', '4.14', '4.19', '5.4', '5.10']
-STABLE_BRANCHES = ['4.4', '4.9', '4.14', '4.19', '5.4', '5.10']
+STABLE_BRANCHES = ['4.4', '4.9', '4.14', '4.19', '5.4', '5.10', '5.11']
 
 UPSTREAM_START_BRANCH = 'v%s' % CHROMEOS_BRANCHES[0]