UI: rename "Edge Collapse" to "Collapse Regions"

This is useful for collapsing regions of faces & edges,
similar to a 'Merge -> Collapse' which can operate on multiple regions,
merging UV's so they don't need to be manually corrected.

The name & description didn't mention this.

source/blender/editors/mesh/editmesh_tools.c

@@ -731,8 +731,9 @@ static int edbm_collapse_edge_exec(bContext *C, wmOperator *op)
 void MESH_OT_edge_collapse(wmOperatorType *ot)
 {
   /* identifiers */
-  ot->name = "Edge Collapse";
-  ot->description = "Collapse selected edges";
+  ot->name = "Collapse Regions";
+  ot->description =
+      "Collapse isolated edges & faces regions, merging data such as UV's and vertex colors";
   ot->idname = "MESH_OT_edge_collapse";
 
   /* api callbacks */