REL: populate changelog

changelog.md

@@ -1,11 +1,26 @@
 
+<a id='changelog-0.3.0'></a>
+# Changes in release "0.3.0"
+
+## Contributors
+
+- @rmcar17 Added new classes to enhance model specification when calling `build_tree` and `fit_tree`.
+- @thomaskf fixed a bug in IQ-TREE resulting in segmentation faults on some invalid arguments.
+
+## ENH
+
+- `build_tree` and `fit_tree` now allow specifying base frequencies, invariable sites and rate heterogeneity options.
+
+## BUG
+
+- Fixed a segmentation fault on repetitive calls to IQ-TREE with particular arguments.
+
 <a id='changelog-0.2.0'></a>
 # Changes in release "0.2.0"
 
 ## Contributors
 
 - Richard Morris
-
 - Robert McArthur
 
 ## ENH