docs: Bluetooth: one-word fix in Channel Sounding

Channel sounding feature was released
several months ago.
Removed word "upcoming" to reflect current
state of the feature. Added links to CS RAS
samples.

Signed-off-by: Ivan Iushkov <[email protected]>

Author: ivaniushkov

doc/nrf/protocols/bt/bt_solutions.rst

@@ -81,5 +81,9 @@ direction from which a Bluetooth signal is transmitted:
 Distance
 ========
 
-Channel sounding is an upcoming feature in the Bluetooth specification that allows distance measurement between two devices.
+Channel sounding is a feature in the Bluetooth specification that allows distance measurement between two devices.
 The measurement is based on round-trip timing (RTT) and phase-based ranging (PBR).
+The following samples can be used to evaluate the feature:
+
+* :ref:`channel_sounding_ras_reflector`
+* :ref:`channel_sounding_ras_initiator`