change to Attenuaton as expected by the code

README.md

@@ -146,15 +146,15 @@ publish-mqtt Urukul/Control/Channel0/Switch "on"
 ```
 This turns on the channel 0 RF switch.
 
-## Attenuator
-- Topic: `Urukul/Control/Channel<ch_num>/Attenuator`
+## Attenuation
+- Topic: `Urukul/Control/Channel<ch_num>/Attenuation`
   - ch_num: The channel number, from 0 to 3.
 - Message: `<atten> [dB]`
   - atten: Attenuation of the attenuator of the specified channel. The unit dB is optional. Valid attenuation is within [0, 31.5] (inclusive) in decibel.
 
 ### Example
 ```shell
-publish-mqtt Urukul/Control/Channel0/Attenuator "20 dB"
+publish-mqtt Urukul/Control/Channel0/Attenuation "20 dB"
 ```
 This sets the attenuation of the channel 0 attenuator to be 20 dB.