v2.0.3 Typo in Readme on bed_sensors

What's Changed

• Corrected Readme to bed_sensors by @Pythm in #31

The correct definition of a bed sensor is a list:

  bed_sensors: 
    - sensor: binary_sensor.bed_occupied

Thanks to @pointlevel for finding the typo!

Full Changelog: v2.0.2...v2.0.3