update changelog

Author: qrohlf

changelog.txt

@@ -1,11 +1,14 @@
 v4
-- ground-up port to ES2015/ES-modules
+- ground-up port to ES2015
+- support for node-canvas 2.6
+- comprehensive test suite
+- support for rendering wireframe patterns (no fill, just stroke)
 - colorFunction has a new method signature that allows for more powerful customization
 - new built-in colorFunctions: 'sparkle' and 'shadows'
 - all-new example code, see examples directory
 - all option keys are now camelCase, not snake_case
-- antialiasing issues solved for both SVG and Canvas rendering engines (#87, #30, #76)
-- browser-based canvas rendering is now retina-ready by default
+- antialiasing issues resolved for both SVG and Canvas rendering engines (#87, #30, #76)
+- canvas rendering is now retina-ready by default
 - removed dependency on seedrandom
 - removed dependency on jsdom