Update changelog

Author: ojustino

CHANGES.rst

@@ -15,7 +15,8 @@ to images instead of predetermined [#128]
 - The default number of bins for FitTrace is now its associated image's number
 of dispersion pixels instead of 20. Its default peak_method is now 'max' [#128]
 - All operations now accept Spectrum1D and Quantity-type images. All accepted
-image types are now processed internally as Spectrum1D objects [#146]
+image types are now processed internally as Spectrum1D objects [#144]
+- All operations' ``image`` attributes are now coerced Spectrum1D objects [#144]
 
 Bug Fixes
 ^^^^^^^^^