Update config.md

The first line of the file was confusing because it referred to Starlark before defining what Starlark was.  I moved the definition to the first line.

Closes #13374.

PiperOrigin-RevId: 369430700
diff --git a/site/docs/skylark/config.md b/site/docs/skylark/config.md
index 44e0f22..ff4f920 100644
--- a/site/docs/skylark/config.md
+++ b/site/docs/skylark/config.md
@@ -7,10 +7,9 @@
 # Configurations
 
 
-This page covers the benefits and basic usage of Starlark configurations. It
-includes how to define build settings and provides examples.
-
-Starlark configuration is Bazel's API for customizing how your project builds.
+This page covers the benefits and basic usage of Starlark configurations,
+Bazel's API for customizing how your project builds. It includes how to define
+build settings and provides examples.
 
 This makes it possible to: