Add clarity for limbs

Signed-off-by: Nicholas Dunning <Nicholas.Dunning@bmw.de>

Author: ndunningbmw

osi_common.proto

@@ -482,6 +482,8 @@ message BoundingBox
 
         // An external limb of a person or animal.
         // 
+        // \note Limbs can be sub-divided to increase accuracy, i.e. for upper 
+        // and lower arm/leg sections.
         TYPE_LIMB = 8;
 
         // The head of a person or animal.
@@ -1103,4 +1105,4 @@ message KeyValuePair
     // A generic string value.
     //
     optional string value = 2;
-}
+}