fixup! proc_mux: add comments

Author: widlarizer

passes/proc/proc_mux.cc

@@ -38,7 +38,7 @@ PRIVATE_NAMESPACE_BEGIN
  * For each snippet, multiplexers ($mux or $pmux) are emitted
  * based on the full switch.
  * $pmux are only emitted when legal based on whether the cases can be
- * evaluated in parallel. Bad HDLs allow users to build cases that can't.
+ * evaluated in parallel.
  * In that case, instead of a $pmux, you get a chain of $mux.
  * Nested switches build branching trees of muxes.
  */