sensor: bq27421: fix available platform in README

bq27421 is available only on nrf9160_innblue22

Signed-off-by: Parthiban Nallathambi <[email protected]>

samples/sensor/bq274xx/README.rst

@@ -25,7 +25,7 @@ from BQ274XX sensor and prints this information to the UART console.
 Requirements
 ************
 
-- nrf9160_innblue21 board with BQ274XX sensor `BQ274XX Sensor`_
+- nrf9160_innblue22 board with BQ274XX sensor `BQ274XX Sensor`_
 
 Building and Running
 ********************
@@ -34,7 +34,7 @@ Build this sample using the following commands:
 
 .. zephyr-app-commands::
    :zephyr-app: samples/sensor/bq274xx
-   :board: nrf9160_innblue21
+   :board: nrf9160_innblue22
    :goals: build flash
 
 References