[chore] fix deployment link for modal.com card (#1031)

docs/get-started/deployment.mdx

@@ -7,7 +7,7 @@ After successfully setting up and testing your RAG app locally, the next step is
 
 <CardGroup cols={4}>
   <Card title="Fly.io" href="/deployment/fly_io"></Card>
-  <Card title="Modal.com" href="#"></Card>
+  <Card title="Modal.com" href="/deployment/modal_com"></Card>
   <Card title="Embedchain Platform" href="#option-1-deploy-on-embedchain-platform"></Card>
   <Card title="Self-hosting" href="#option-2-self-hosting"></Card>
 </CardGroup>