GH-913 - Package Javadoc for newly introduced packages.

spring-modulith-junit/src/main/java/org/springframework/modulith/junit/diff/package-info.java

@@ -0,0 +1,6 @@
+/**
+ * Project differences detection implementation.
+ *
+ * @since 1.3
+ */
+package org.springframework.modulith.junit.diff;

spring-modulith-junit/src/main/java/org/springframework/modulith/junit/package-info.java

@@ -0,0 +1,6 @@
+/**
+ * JUnit extension to optimize test case execution depending of the changes made to an application.
+ *
+ * @since 1.3
+ */
+package org.springframework.modulith.junit;