Skinning influenced by more than 4 joints

A brief description of what happens in the event that skins are influenced by more than 4 joints

specification/2.0/README.md

@@ -913,11 +913,13 @@ The mesh for a skin is defined with vertex attributes that are used in skinning
 }
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-The number of joints that influence one vertex is limited to 4, so referenced accessors must have `VEC4` type and following component formats:
+The number of joints that influence one vertex is limited to 4 per set, so referenced accessors must have `VEC4` type and following component formats:
 
 * **`JOINTS_0`**: `UNSIGNED_BYTE` or `UNSIGNED_SHORT`
 * **`WEIGHTS_0`**: `FLOAT`, or normalized `UNSIGNED_BYTE`, or normalized `UNSIGNED_SHORT`
 
+In the event that of any of the vertices are influenced by more than four joints, the additional joint and weight information will be found in subsequent sets. For example `JOINTS_1` and `WEIGHTS_1` if present will reference the accessor for up to 4 additional joints that influence the vertices.
+
 #### Joint Hierarchy
 
 The joint hierarchy used for controlling skinned mesh pose is simply the glTF node hierarchy, with each node designated as a joint. The following example defines a joint hierarchy of two joints.