Fix some typos in README_EN.md

Thank you for the useful tutorial. I fixed some typos in README_EN.md. Would you accept the pull request?
- "this is ablout learn Spring Boot Examples" -> "This tutorial is about learning Spring Boot via examples."
- "Spring Boot Example. Use the simplest and useful sene demos" -> "Spring Boot examples, using the simplest and the most useful scene demos"

README_EN.md

 # Spring Boot Examples
 
-this is ablout learn Spring Boot Examples
+This tutorial is about learning Spring Boot via examples.
 
 
 [Spring Cloud example code](https://github.com/ityouknow/spring-cloud-examples)   |   [中文](README.md)
 
-Spring Boot Examples, Use the simplest and most useful scene demo.
+Spring Boot examples, using the simplest and the most useful scene demos.
 
 ---