Restructure Release Notes (#5832)

* 1st try at restructuring

* Add emojis and do-not-miss section

* Apply suggestions from code review

Co-authored-by: Michael Osthege <[email protected]>
Co-authored-by: Ricardo Vieira <[email protected]>

* Improve structure based on review

* Apply suggestions from code review

Co-authored-by: Ricardo Vieira <[email protected]>

* Improve structure again

* Add release announcement

* Apply suggestions from code review

Co-authored-by: Thomas Wiecki <[email protected]>

* Apply suggestions from code review

Co-authored-by: Thomas Wiecki <[email protected]>

* Apply suggestions from code review

Co-authored-by: Thomas Wiecki <[email protected]>

* Add highlight of JAX backend.

* Remove BART section and move links to where we remove it.

* Move BART further down. Remove mention of size.

Co-authored-by: Michael Osthege <[email protected]>
Co-authored-by: Ricardo Vieira <[email protected]>
Co-authored-by: Thomas Wiecki <[email protected]>

Author: 4 people