update readme

Author: mysterywolf

README.md

@@ -17,7 +17,7 @@ RT-Thread was born in 2006, it is an open source, neutral, and community-based r
 
 RT-Thread is mainly written in C language, easy to understand and easy to port(can be quickly port to a wide range of mainstream MCUs and module chips). It applies object-oriented programming methods to real-time system design, making the code elegant, structured, modular, and very tailorable.
 
-RT-Thread has Standard version and Nano version. For resource-constrained microcontroller (MCU) systems, the NANO kernel version that requires only 3KB Flash and 1.2KB RAM memory resources can be tailored  with easy-to-use tools; And for resource-rich IoT devices, RT-Thread can use the on-line software package management tool, together with system configuration tools, to achieve intuitive and rapid modular cutting, seamlessly import rich software packages, thus achieving complex functions like Android's graphical interface and touch sliding effects, smart voice interaction effects, and so on.
+RT-Thread has Standard version and Nano version. For resource-constrained microcontroller (MCU) systems, the Nano version that requires only 3KB Flash and 1.2KB RAM memory resources can be tailored with easy-to-use tools. For resource-rich IoT devices, RT-Thread can use the on-line software package management tool, together with system configuration tools, to achieve intuitive and rapid modular cutting, seamlessly import rich software packages; thus, achieving complex functions like Android's graphical interface and touch sliding effects, smart voice interaction effects, and so on.
 
 ## RT-Thread Architecture