Put "Library Evolution" in review as SE-0260

Author: rjmccall

proposals/NNNN-library-evolution.md renamed to proposals/0260-library-evolution.md

@@ -1,9 +1,9 @@
 # Library Evolution for Stable ABIs
 
-* Proposal: [SE-NNNN](NNNN-library-evolution.md)
+* Proposal: [SE-0260](0260-library-evolution.md)
 * Authors: [Jordan Rose](https://github.com/jrose-apple), [Ben Cohen](https://github.com/airspeedswift)
-* Review Manager: TBD
-* Status: **Awaiting review**
+* Review Manager: [John McCall](https://github.com/rjmccall)
+* Status: **Active Review (May 7...21, 2019)**
 * Implementation: Implemented in Swift 5 for standard library use. PR with renamed attributes [here](https://github.com/apple/swift/pull/24185).
 * Pre-review discussion: [Forum thread](https://forums.swift.org/t/pitch-library-evolution-for-stable-abis/)