Fix README.

Author: yuuu

README.md

@@ -1,4 +1,4 @@
-# mruby-esp32-pwm
+# mruby-esp32-mcpwm
 
 PWM library for mruby-esp32.
 
@@ -9,23 +9,23 @@ You need [esp-idf v5.0](https://docs.espressif.com/projects/esp-idf/en/release-v
 Add the line below to your `build_config.rb`:
 
 ```ruby
-  conf.gem :github => 'mruby-esp32/mruby-esp32-pwm'
+  conf.gem :github => 'mruby-esp32/mruby-esp32-mcpwm'
 ```
 
 ## Examples
 
 ```ruby
-pwm = PWM.new(1)  # GPIO pin = 1
-pwm.frequency(50) # set frequency(Hz) of PWM
-pwm.duty(10)      # set duty(%) of PWM
+mcpwm = MCPWM.new(1)  # GPIO pin = 1
+mcpwm.frequency(50) # set frequency(Hz) of PWM
+mcpwm.duty(10)      # set duty(%) of PWM
 # => drive with frequency=50Hz(Period=20_000us), duby=10%(Pulse Width=2000us)
 
-pwm = PWM.new(1, freq: 100, duty: 40)
+mcpwm = MCPWM.new(1, freq: 100, duty: 40)
 # => drive with frequency=100Hz(Period=10_000us), duby=40%(Pulse Width=4000us)
 
-pwm = PWM.new(1)
-pwm.period_us(25_000)
-pwm.pulse_width_us(5_000)
+mcpwm = PWM.new(1)
+mcpwm.period_us(25_000)
+mcpwm.pulse_width_us(5_000)
 # => drive with frequency=40Hz(Period=25_000us), duby=20%(Pulse Width=5000us)
 ```