Update docs/config/extensions/overview.mdx

Co-authored-by: coderabbitai[bot] <136622811+coderabbitai[bot]@users.noreply.github.com>

Author: ericallam

docs/config/extensions/overview.mdx

@@ -4,7 +4,7 @@ sidebarTitle: "Overview"
 description: "Customize how your project is built and deployed to Trigger.dev with build extensions"
 ---
 
-Build extension allow you to hook into the build system and customize the build process or the resulting bundle and container image (in the case of deploying).
+Build extensions allow you to hook into the build system and customize the build process or the resulting bundle and container image (in the case of deploying).
 
 You can use pre-built extensions by installing the `@trigger.dev/build` package into your `devDependencies`, or you can create your own.