Change description of UNIT_MINUTES

Issue: #638
Signed-off-by: FlorianMueller87 <[email protected]>

Author: FlorianMueller87

osi_trafficsign.proto

@@ -103,7 +103,7 @@ message TrafficSignValue
         UNIT_SHORT_TON = 11;
 
         // Time of day.
-        // Hour since midnight.
+        // Minutes since last hour.
         //
         // Unit: min
         //