Update README.adoc with link to CONTRIBUTING.adoc

Update the README to help potential contributors find information.

See gh-45969

Signed-off-by: Rutuja  <[email protected]>

Author: Rutujakolte03

README.adoc

@@ -61,6 +61,12 @@ Are you having trouble with Spring Boot? We want to help!
 
 
 
+== Contributing
+
+We welcome contributions of all kinds! Please read our [contribution guidelines](CONTRIBUTING.md) before submitting a pull request.
+
+
+
 == Reporting Issues
 
 Spring Boot uses GitHub's integrated issue tracking system to record bugs and feature requests.