Adds CHANGELOG entry for 1.0.0

Author: weierophinney

CHANGELOG.md

@@ -2,11 +2,29 @@
 
 All notable changes to this project will be documented in this file, in reverse chronological order by release.
 
-## 0.1.0 - TBD
+## 1.0.0 - 2018-02-05
+
+Initial stable release.
+
+The `Zend\HttpRequestHandler\Emitter` subcomponent was originally released as
+part of two packages:
+
+- `EmitterInterface` and the two SAPI emitter implementations were released
+  previously as part of the [zend-diactoros](https://docs.zendframework.com/zend-daictoros)
+  package.
+
+- `EmitterStack` was previously released as part of the
+  [zend-expressive](https://docs.zendframework.com/zend-expressive/) package.
+
+These features are mostly verbatim from that package, with minor API changes.
+
+The `RequestHandlerRunner` was originally developed as part of version 3
+development of zend-expressive, but extracted here for general use with
+[PSR-15](https://www.php-fig.org/psr/psr-15) applications.
 
 ### Added
 
-- Nothing.
+- Everything.
 
 ### Changed