message: update recent changes in changelog
diff: Changelog
  =========
  -- 0.6.0-alpha
  +- 0.6.0
  - enable the selection of the integer type for storing indices in matrix
  - types.
  + types **breaking change**
  + - update to ndarray 0.8
  - 0.5.0
  - adapt to breaking changes in ndarray 0.7
  - 0.4.1:
  