Add Bounce [BNCE] axis (#63)

Add Bounce [BNCE] axis (#63)

* Add BNCE custom axis

* Default fallback only + Dave's Description

* Decimals added to values

To make the defined precision value more explicit.

* Update bounce.textproto with reference project URL

* Updating precision value to 0

After the decision agreed upon in the Axis Finalization document

* Update BNCE description

Following agreed decisions on meeting

Co-authored-by: Viviana Monsalve <viviana.monsalve.a@gmail.com>
Co-authored-by: Dave Crossland <dave@lab6.com>