doc: relnotes: Add a comment to the Bluetooth 2.6 release notes

The Zephyr 2.6 release notes, in the Bluetooth section, refers the user
to a commit message which had a couple of typos in it. Clarify this in
the very release notes.

Fixes #36692.

Signed-off-by: Carles Cufi <carles.cufi@nordicsemi.no>