Add changelog entry for #180

Author: mattt

Changelog.md

@@ -9,9 +9,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Fixed
 
+- Fixed missing GraphViz dependency in Dockerfile.
+  #180 by @MaxDesiatov.
 - Fixed listing of function parameters, when generating CommonMark documentation.
   #170 by @domcorvasce.
-
 - Fixed version number for swift-doc command.
   #159 by @mattt.