Assign SIP number to the @unchecked SIP

Author: anatoliykmetyuk

content/replace-nonsensical-unchecked-annotation.md

@@ -4,7 +4,7 @@ permalink: /sips/:title.html
 stage: implementation
 status: waiting-for-implementation
 presip-thread: https://contributors.scala-lang.org/t/pre-sip-replace-non-sensical-unchecked-annotations/6342
-title: SIP-NN - Replace non-sensical @unchecked annotations
+title: SIP-57 - Replace non-sensical @unchecked annotations
 ---
 
 **By: Martin Odersky and Jamie Thompson**