update source comments

src/lhca.sv

@@ -3,9 +3,12 @@ module lhca #(
  parameter bit [WIDTH-1:0] DIAGONAL = WIDTH'(0)
 ) (
  input logic clk,
- // a source of true randomness, i.e. ring oscillators
- // without it, the output will be pseudo-random,
- // and LHCA acts as a scrambler
+
+ // A source of true randomness, makes the LHCA act as a scrambler.
+ // You can use ring oscillators for this when the oscillation
+ // frequency is significantly higher than the clock frequency.
+
+ // Without it, the output will be pseudo-random,
  input logic [WIDTH-1:0] source,
  output logic [WIDTH-1:0] state
 );