[0042] Mark as under review

After the meeting today we seem to have alignment here. I'm going to
mark this proposal as under review with PR microsoft#634 as the main review for
the spec contribution.

Author: llvm-beanz

proposals/0042-restricted-unbounded-arrays.md

@@ -5,7 +5,7 @@ params:
     - llvm-beanz: Chris Bieneman
   sponsors:
     - llvm-beanz: Chris Bieneman
-  status: Under Consideration
+  status: Under Review
 ---
 
 * Planned Version: 202x