docs/zink: remove bptc from required formats for gl4.2
We now have lowering-code in the mesa state-tracker, meaning we no longer need this feature.
Fixes: e4ff4268 ("mesa/st: enable bptc extension with fallback")
We now have lowering-code in the mesa state-tracker, meaning we no longer need this feature.
Fixes: e4ff4268 ("mesa/st: enable bptc extension with fallback")