Prepare for 0.18 release

CHANGELOG.md

@@ -5,12 +5,15 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 This file follows the convention described at
 [Keep a Changelog](http://keepachangelog.com/en/1.0.0/).
 
-## [Unreleased]
+## [0.18.0] - 2023-04-15
 ### Changed
 - **Breaking**: jshrake: Add `map` argument to `import_image_pixels()` and
   change `pixels` argument to a byte slice rather than a vector reference.
 ### Added
 - jshrake: Add `MagickAutoGammaImage` and `MagickAutoLevelImage`
+- 2e0by0: add API documentation and setup automated build of docs.
+### Fixed
+- BeatButton: prevent segfault if `MagickGetImageBlob` returns `null`
 
 ## [0.17.0] - 2022-12-10
 ### Added