Update README.md Small updates to readme

Merge branch '45-bump-to-4.0.0' 

pre-release v0.7.0a7 

pre-release v0.7.0a6 

pre-release vectorsearch (alpha 5) 

Release v0.6.1 

release v0.6.0 

README.md: minor updates 

Update version to 0.4.0 

add publishing to the makefile