Add comments to test vector output linking to source

sapling_generators.py

@@ -61,6 +61,7 @@ def main():
             vcrb: [u8; 32],
         };
 
+        // From https://github.com/zcash-hackworks/zcash-test-vectors/blob/master/sapling_generators.py
         let sapling_generators = SaplingGenerators {
             skb: [
                 %s

sapling_key_components.py

@@ -102,6 +102,7 @@ def main():
             note_nf: [u8; 32],
         };
 
+        // From https://github.com/zcash-hackworks/zcash-test-vectors/blob/master/sapling_key_components.py
         let test_vectors = vec![''')
     for i in range(0, 10):
         sk = SpendingKey(bytes([i] * 32))

sapling_signatures.py

@@ -85,6 +85,7 @@ def main():
             rsig: [u8; 64],
         };
 
+        // From https://github.com/zcash-hackworks/zcash-test-vectors/blob/master/sapling_signatures.py
         let test_vectors = vec![''')
     for i in range(0, 10):
         sk = rj.gen_private()