Merge pull request #560 from stm32-rs/readme

fix readme

Author: burrbull

README.md

@@ -74,7 +74,7 @@ cortex-m-rt = "0.7"
 panic-halt = "0.2"
 
 [dependencies.stm32f4xx-hal]
-version = "0.13.2"
+version = "0.14.0"
 features = ["stm32f407"] # replace the model of your microcontroller here
 ```