update changelog for 3.6.0 release (engine-3.6) [demos]

update changelog and docs for 3.5.2 release (engine-3.5)

update changelog for 3.5.1 release (engine-3.5)

update readme and links for 3.5.0 release (engine-3.5)[demos]

update changelog to include compatibility with decorator >=4.2

update installers versions in the documentation to 3.3.2

update installers versions in the documentation to 3.3.1

update readme and links for 3.3.0 release (engine-3.3)[demos]

update readme and links for 3.2.0 release (engine-3.2) [demos]

update README and links for 3.1.0 release (engine-3.1)