update readme

Author: otbe

README.md

@@ -106,4 +106,5 @@ assertEquals("Peter",p2.name.get());
 | Library version | Spring Boot version |
 |-----------------|---------------------|
 | 1.x.x           | 2.7+                |
-| 2.x.x           | 3.1+                |
+| 2.x.x           | 3.1+                |
+| 3.x.x           | 4.0+                |