Update changelog [skip ci]

Author: Onur Rauf Bingol

CHANGELOG.md

@@ -2,7 +2,10 @@
 
 ## v5.2.8 released on 2019-07-10
 
-* Fix normal vector evaluation for curves (as discussed in #49 and #50)
+* Update `control_points` module
+* Fix a bug in `operations.refine_knotvector` failing to work with Bezier-type geometries
+* Fix a bug in normal vector evaluation for curves (as discussed in #49 and #50)
+* Minor improvements and documentation updates
 
 ## v5.2.7 released on 2019-05-24