docs: update with dht20 pics

Author: zeldan

README.md

@@ -125,6 +125,8 @@ After outputting a low signal for 50 microseconds, the DHT11/DHT22 completes sen
 
 ### DHT20
 
+![steps](/docs/dht20_steps.png)
+
 - SDA = Serial Data Line
 - SCL = Serial Clock Line
 
@@ -141,12 +143,16 @@ After powering on, wait at least 100ms. Before reading the temperature and humid
 #### Step 2
 Wait for 10ms before sending the 0xAC command to trigger the measurement. The command consists of two bytes: the first byte is 0x33 and the second byte is 0x00.
 
+![step4](/docs/dht20_step2.png)
+
 #### Step 3
 Wait for 80ms for the measurement to complete. If Bit [7] of the status word is 0, the measurement is done, and you can proceed to read six bytes continuously; if not, continue waiting.
 
 #### Step 4
 After receiving the six bytes, the following byte is the CRC check data, which can be read if needed. If the receiver requires CRC validation, an ACK is sent after the sixth byte is received; otherwise, send a NACK to terminate. The initial CRC value is 0xFF, and the CRC8 check uses the polynomial: CRC [7:0] = 1 + X^4 + X^5 + X^8.
 
+![step4](/docs/dht20_step4.png)
+
 #### Step 5
 Compute the temperature and humidity values.