doc/rados: edit bluestore-config-ref.rst (1 of x)

Edit the first part of doc/rados/configuration/bluestore-config-ref.rst.

https://tracker.ceph.com/issues/58485

Co-authored-by: Anthony D'Atri <[email protected]>
Signed-off-by: Zac Dover <[email protected]>

Author: zdover23