Add release notes for v0.5

Update date of release

[skip ci]

Add AppVeyor badge to README.rst

DOC: add release notes for v0.2

Initial release v0.1

https://github.com/tum-camp/survival-support-vector-machine/releases/…

…tag/v2.0

https://github.com/tum-camp/survival-support-vector-machine/releases/…

…tag/v1.0