Commented WFI non-flush in writeback stage of hazard unit

src/hazard/hazard.sv

@@ -71,6 +71,7 @@ module hazard (
   // Similarly, CSR writes and fences flush all subsequent instructions and refetch them in light of the new operating modes and cache/TLB contents
   // Branch misprediction is found in the Execute stage and must flush the next two instructions.
   //   However, an active division operation resides in the Execute stage, and when the BP incorrectly mispredicts the divide as a taken branch, the divde must still complete
+  // When a WFI is interrupted and causes a trap, it flushes the rest of the pipeline but not the W stage, because the WFI needs to commit
   assign FlushDCause = TrapM | RetM | CSRWriteFenceM | BPWrongE;
   assign FlushECause = TrapM | RetM | CSRWriteFenceM |(BPWrongE & ~(DivBusyE | FDivBusyE));
   assign FlushMCause = TrapM | RetM | CSRWriteFenceM;