JAVA-6511 update readme, add context test

spring-5-data-reactive/src/test/java/com/baeldung/SpringContextTest.java

@@ -0,0 +1,17 @@
+package com.baeldung;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.test.context.junit4.SpringRunner;
+
+import com.baeldung.r2dbc.R2dbcApplication;
+
+@RunWith(SpringRunner.class)
+@SpringBootTest(classes = R2dbcApplication.class)
+public class SpringContextTest {
+
+    @Test
+    public void whenSpringContextIsBootstrapped_thenNoExceptions() {
+    }
+}