add link to projects using redo; fix t/example mention (#20)

also rename t/111-compile2 to t/111-example

t/111-example/main.c

@@ -0,0 +1,8 @@
+#include <stdio.h>
+#include "mystr.h"
+
+int main()
+{
+    printf("%s\n", mystr);
+    return 0;
+}