samples: sensor: ms5837: Fix wording in README

The nRF52840 Preview development kit is no longer available and the
text in the README.rst is changed to be "nRF52840 Development kit" and
the link to the documentation is changed to point to the production
version.

Signed-off-by: Ole Sæther <ole.saether@nordicsemi.no>

Author: osaether

samples/sensor/ms5837/README.rst

@@ -13,13 +13,13 @@ sensor every 10 seconds, and prints this information to the UART console.
 Requirements
 ************
 
-- `nRF52840 Preview development kit`_
+- `nRF52840 Development kit`_
 - MS5837 sensor
 
 Wiring
 ******
 
-The nrf52840 Preview development kit should be connected as follows to the
+The nrf52840 Development kit should be connected as follows to the
 MS5837 sensor.
 
 +-------------+----------+
@@ -50,4 +50,4 @@ References
 .. target-notes::
 
 .. _MS5837 Sensor: http://www.te.com/usa-en/product-CAT-BLPS0017.html?q=&type=products&samples=N&q2=ms5837
-.. _nRF52840 Preview development kit: http://www.nordicsemi.com/eng/Products/nRF52840-Preview-DK
+.. _nRF52840 Development kit: https://www.nordicsemi.com/Products/Development-hardware/nRF52840-DK