update definition of C++ gradle projects

gradle-c-plugin/01-hello-task/build.gradle

@@ -0,0 +1,9 @@
+task hello {
+    // Loaded in configuration phase
+    description = "Say Hello :-)"
+    doLast {
+        // Executed in execution phase
+        println "Hello FI MUNI!"
+    }
+}
+