bump to version 4.0.8

Version 4.0.7

bump to version 4.0.6

fix typo

fix makefile (LycheeOrg#547)

bump version (LycheeOrg#513)

oups

version 4.0.1 ready (LycheeOrg#484)

small fixes for the release of v4 (LycheeOrg#479)

* small fixes for the release of v4
* correct urls
* Update readme URLs
* Add link to changelog for v3 users
* improving the install procedure, fixing the removing procedure

Co-authored-by: Martin Stone <martin@d7415.co.uk>

Update version.md