doc: fem: add nrf54lm20 to supported list

For the nRF54LM20 SoC support for the following FEM implementations
is claimed: nRF2220, nRF21540 GPIO+SPI.

Signed-off-by: Andrzej Kuros <[email protected]>

Author: ankuns

doc/nrf/app_dev/device_guides/fem/index.rst

@@ -70,22 +70,27 @@ Zephyr and the |NCS| provides support for developing applications with the follo
            - Implementation
            - nRF54L10
            - nRF54L15
+           - nRF54LM20
          * - nRF2220
            - nRF2220
            - Supported
            - Supported
+           - Supported
          * - nRF21540
            - nRF21540 GPIO
            - Supported
            - Supported
+           - --
          * - nRF21540
            - nRF21540 GPIO+SPI
            - Supported
            - Supported
+           - Supported
          * - SKY66112-11
            - Simple GPIO
            - Supported
            - Supported
+           - --
 
 The FEM support on SoCs that are not listed in the table above might still work, but it is not tested and not guaranteed to work.