Update SIPs state

Author: scala-improvement-bot

_sips/sips/alternative-bind-variables.md

@@ -1,8 +1,8 @@
 ---
 layout: sip
 permalink: /sips/:title.html
-stage: pre-sip
-status: submitted
+stage: implementation
+status: waiting-for-implementation
 presip-thread: https://contributors.scala-lang.org/t/pre-sip-bind-variables-for-alternative-patterns/6321/13
 title: SIP-60 - Bind variables within alternative patterns
 ---