updated readme

README.md

@@ -178,4 +178,4 @@ For other moduli (e.g. those used in RSA verification), both `modulus` and `redc
 
 `double_modulus` is derived via the method `compute_double_modulus` in `runtime_bignum.nr`. If you want to provide this value as a compile-time constant (see `fields/bn254Fq.nr` for an example), follow the algorithm `compute_double_modulus` as this parameter is _not_ structly 2 \* modulus. Each limb except the most significant limb borrows 2^120 from the next most significant limb. This ensure that when performing limb subtractions `double_modulus.limbs[i] - x.limbs[i]`, we know that the result will not underflow.
 
-For example derivations see `https://github.com/noir-lang/noir_rsa`
+BigNumInstance parameters can be derived from a known modulus using the rust crate `noir-bignum-paramgen` (https://crates.io/crates/noir-bignum-paramgen)