docs: link the testing quick start

CONTRIBUTING.md

diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index 9c47af8..6f066c1 100644
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -22,3 +22,4 @@
 ## Quick links
 
 - [Set up your development environment](https://datafusion.apache.org/contributor-guide/development_environment.html#quick-start)
+- [Run tests](https://datafusion.apache.org/contributor-guide/testing.html#testing-quick-start)