Update 1.1.1.md

Author: japgolly

doc/changelog/1.1.1.md

@@ -1,12 +1,16 @@
 ## v1.1.1
 
+*This will be the last release targeting React v15. The next release (v1.2.0) will require React v16.*
+
+<br>
+
 * When VDOM has been imported, VDOM collections (eg. `List[VdomTag]`) gain two `.mkTagMod` methods that are VDOM
   equivalents of `.mkString` in Scala's stdlib.
   * `mkTagMod(sep: TagMod): TagMod`
   * `mkTagMod(start: TagMod, sep: TagMod, end: TagMod): TagMod`
 
 * Add `Reusability.derive[A]` and `Reusability.deriveDebug[A]` which handles sealed traits and sealed abstract classes
-  in addition to case classes. `Reusability.caseClass{,Debug}` is therefore deprecated.
+  in addition to case classes. `Reusability.caseClass{,Debug}` is therefore deprecated. (Migration command below)
 
 * Add to `StateSnapshot[S]` instances:
   * `.xmapState[T](f: S => T)(g: T => S)     : StateSnapshot[T]` (Disables `Reusability` on the result)
@@ -42,4 +46,4 @@
 
 ```sh
 find . -name '*.scala' -type f -exec perl -pi -e 's/(Reusability[ .]*)caseClass(Debug)?(?!E)/$1derive$2/g' {} +
-```
+```