nrf_modem: Add Dect clock sync documentation

Adds documentation for Dect clock synchronization.

Signed-off-by: Tommi Kaivola <tommi.kaivola@nordicsemi.no>

Author: tokaivola

doc/links.txt

@@ -42,6 +42,7 @@
 
 .. _`nRF9161 DECT NR+ product specification`:  https://docs.nordicsemi.com/bundle/ps_nrf9161/page/dect.html
 .. _`nRF9151 DECT NR+ product specification`:  https://docs.nordicsemi.com/bundle/ps_nrf9151/page/dect.html
+.. _`nRF9151 product specification`:  https://docs.nordicsemi.com/bundle/ps_nrf9151/page/nRF9151_html5_keyfeatures.html
 
 .. _`nRF9160 modem firmware zip file`: https://www.nordicsemi.com/Products/Low-power-cellular-IoT/nRF9160/Download#0B34B59935AF4AFCB7AB93E9646C1F53
 .. _`nRF91x1 LTE firmware zip file`: https://www.nordicsemi.com/Products/nRF9161/Download#636701B052474E5A8EB903C56678D26E

nrf_modem/README.rst

@@ -20,6 +20,7 @@ For more information about porting, see :ref:`nrf_modem_ug_porting`.
    doc/bootloader
    doc/delta_dfu
    doc/dectphy
+   doc/dect_clock_sync
    doc/softsim_interface
    doc/fault_handling
    doc/modem_trace