Update location of hello-greet.h

Fixes #13014

PiperOrigin-RevId: 369856938
diff --git a/site/docs/cpp-use-cases.md b/site/docs/cpp-use-cases.md
index 102e7ea..4c67c55 100644
--- a/site/docs/cpp-use-cases.md
+++ b/site/docs/cpp-use-cases.md
@@ -199,7 +199,7 @@
 
 ```cpp
 #include "gtest/gtest.h"
-#include "lib/hello-greet.h"
+#include "main/hello-greet.h"
 
 TEST(HelloTest, GetGreet) {
   EXPECT_EQ(get_greet("Bazel"), "Hello Bazel");