fix(drizzle-kit-studio.mdx): add dialect to config

Author: Ba3a-G

src/content/docs/drizzle-kit-studio.mdx

@@ -25,6 +25,7 @@ By default it will start a Drizzle Studio server on `127.0.0.1:4983`
 import { defineConfig } from "drizzle-kit";
 
 export default defineConfig({
+  dialect: "postgresql",
   dbCredentials: {
     url: "postgresql://user:password@host:port/dbname"
   },