Inaugurate SE-0223, array uninitialized buffer initializer

Author: jckarter

proposals/0000-array-uninitialized-initializer.md renamed to proposals/0223-array-uninitialized-initializer.md

@@ -1,9 +1,9 @@
 # Accessing an Array's Uninitialized Buffer
 
-* Proposal: [SE-NNNN](NNNN-array-uninitialized-buffer.md)
+* Proposal: [SE-0223](0223-array-uninitialized-buffer.md)
 * Author: [Nate Cook](https://github.com/natecook1000)
-* Review Manager: TBD
-* Status: **Awaiting review**
+* Review Manager: [Joe Groff](https://github.com/jckarter)
+* Status: **Active review (August 13...August 19, 2018)**
 * Implementation: https://github.com/apple/swift/pull/17389
 * Bug: [SR-3087](https://bugs.swift.org/browse/SR-3087)