Add requirements section to README.md

Author: nstdio

README.md

@@ -12,6 +12,11 @@ JDK's [HttpClient](https://docs.oracle.com/en/java/javase/11/docs/api/java.net.h
 | Code coverage | [![codecov](https://codecov.io/gh/nstdio/http-client-ext/branch/main/graph/badge.svg)](https://codecov.io/gh/nstdio/http-client-ext)                                                                                                                                                                                                                         |
 | LGTM          | [![Total alerts](https://img.shields.io/lgtm/alerts/g/nstdio/http-client-ext.svg?logo=lgtm&logoWidth=18)](https://lgtm.com/projects/g/nstdio/http-client-ext/alerts/) [![Language grade: Java](https://img.shields.io/lgtm/grade/java/g/nstdio/http-client-ext.svg?logo=lgtm&logoWidth=18)](https://lgtm.com/projects/g/nstdio/http-client-ext/context:java) |
 
+### Requirements
+
+- Java 11+ 
+- [Gradle](https://gradle.org/) for building the project.
+
 ### Gradle
 
 ```