Improve example documentation (#108)

This PR updates the example documentation to clarify generator independence.

Author: AaronFeickert

examples/ringct.rs

@@ -29,6 +29,8 @@ mod test {
         let number_outputs = params.get_N();
 
         // Value commitments use the Triptych `G` generator for masks, and need another component for values
+        // In practice it's essential that `G` and `H` have no efficiently-computable discrete logarithm relationship
+        // For this example, we'll just make it random; in the real world, you'd use a verifiable hash-based construction
         let H = RistrettoPoint::random(&mut rng);
 
         // All output verification keys and value commitments (except ours) look random to us, so just make them random!