Swift: Add GOOD and BAD comments in the sensitive data hashing examples as well.

Author: geoffw0

swift/ql/src/queries/Security/CWE-328/WeakSensitiveDataHashingBad.swift

@@ -3,8 +3,8 @@ func getContentsAndHash(url: URL) -> (Data, String)? {
         return nil
     }
 
-    let digest = Insecure.MD5.hash(data: data)
+    let digest = Insecure.MD5.hash(data: data) // BAD: MD5 is not suitable for hashing sensitive data.
     let hash = digest.map { String(format: "%02hhx", $0) }.joined()
 
     return (data, hash)
-}
+}

swift/ql/src/queries/Security/CWE-328/WeakSensitiveDataHashingGood.swift

@@ -3,8 +3,8 @@ func getContentsAndHash(url: URL) -> (Data, String)? {
         return nil
     }
 
-    let digest = SHA512.hash(data: data)
+    let digest = SHA512.hash(data: data) // GOOD: SHA-512 is suitable for hashing sensitive data.
     let hash = digest.map { String(format: "%02hhx", $0) }.joined()
 
     return (data, hash)
-}
+}