Add changelog for version 0.6.0
Please also check the [GitHub Releases Page](https://github.com/se2p/pynguin/releases)
for the source-code artifacts of each version.
+## Pynguin 0.6.0
+
+- Add support for simple assertion generation (thanks to [@Wooza](https://github.com/Wooza)).
+ For now, assertions can only be generated for simple types (`int`, `float`, `str`,
+ `bool`). All other assertions can only check whether or not a result of a method
+ call is `None`.
+ The generated assertions are regression assertions, i.e., they record the return
+ values of methods during execution and assume them to be correct.
+- Provide a version-independent DOI on Zenodo in the read me
+- Several bug fixes
+- Provide this changelog
+
## Pynguin 0.5.3
- Extends the documentation with a more appropriate example
