tensor: Doc update

hw/rtl/core/VX_decode.sv

@@ -551,11 +551,14 @@ module VX_decode  #(
                 end else begin
                     op_type = `INST_TENSOR_HGMMA;
                 end
-                // rd/rs1/rs2/rs3 unused
+                // rd/rs1/rs2/rs3 unused to prevent hazard stalls at the
+                // scoreboard
             `else
                 ex_type = `EX_TENSOR;
                 op_type = `INST_TENSOR_HMMA;
                 // tensor core macroop is encoded as r-type
+                // hazard stall logic in the scoreboard will handle
+                // read-after-write dependency on rd -> rs3
                 use_rd = 1;
                 `USED_IREG (rd);
                 `USED_IREG (rs1);