cleaned up changelog for release 0.40.0
cleaned up changelog for release 0.40.0

puneetjaiswal/crate,puneetjaiswal/crate,adrpar/crate,puneetjaiswal/crate,EvilMcJerkface/crate,crate/crate,crate/crate,adrpar/crate,aslanbekirov/crate,EvilMcJerkface/crate,EvilMcJerkface/crate,gmrodrigues/crate,sunny256/crate,husky-koglhof/crate,sunny256/crate,crate/crate,husky-koglhof/crate,aslanbekirov/crate,husky-koglhof/crate,gmrodrigues/crate,aslanbekirov/crate,adrpar/crate,gmrodrigues/crate,sunny256/crate