Fix example link in gazelle readme (#693)

Use a permalink instead of relative file path

gazelle/README.md

diff --git a/gazelle/README.md b/gazelle/README.md
index 7d138e3..51055cb 100644
--- a/gazelle/README.md
+++ b/gazelle/README.md
@@ -90,7 +90,7 @@
 That's it, now you can finally run `bazel run //:gazelle` anytime
 you edit Python code, and it should update your `BUILD` files correctly.
 
-A fully-working example is in [`examples/build_file_generation`](examples/build_file_generation).
+A fully-working example is in [`examples/build_file_generation`](../examples/build_file_generation).
 
 ## Usage