We must document our support policy and remove obsolete support and licensing information

[fdesbiens]

The documentation still mentions the old Microsoft support policy and licensing model. We must fix that.

In particular, this file must be replaced.
https://github.com/eclipse-threadx/rtos-docs-asciidoc/blob/main/rtos-docs/general/media/roadmap.png

We can use Frédéric's blog on the new release cadence as a source of inspiration.