note about latest details being on master branch

doc/update/2.6-to-3.0.md

doc/update/2.9-to-3.0.md

doc/update/3.0-to-3.1.md

doc/update/3.1-to-4.0.md

doc/update/4.0-to-4.1.md

doc/update/4.1-to-4.2.md

doc/update/4.2-to-5.0.md

doc/update/5.0-to-5.1.md

doc/update/5.1-to-5.2.md

doc/update/5.1-to-5.4.md

doc/update/5.1-to-6.0.md

doc/update/5.2-to-5.3.md

doc/update/5.3-to-5.4.md

doc/update/5.4-to-6.0.md

doc/update/6.0-to-6.1.md

doc/update/6.1-to-6.2.md

doc/update/6.2-to-6.3.md

doc/update/6.3-to-6.4.md

doc/update/6.4-to-6.5.md

doc/update/6.5-to-6.6.md