docs: added previews: false to the documentation

Author: noam-honig

docs/tutorialkit.dev/src/content/docs/reference/configuration.mdx

@@ -230,6 +230,7 @@ The `Preview` type has the following shape:
 type Preview =
     | number
     | string
+    | false
     | [port: number, title: string]
     | [port: number, title: string, pathname: string]
     | { port: number, title: string, pathname?: string }
@@ -242,6 +243,7 @@ Example value:
 previews:
   - 3000 # Preview is on :3000/
   - "3001/docs" # Preview is on :3001/docs/
+  - false # do not show peview panel
   - [3002, "Dev Server"] # Preview is on :3002/. Displayed title is "Dev Server".
   - [3003, "Dev Server", "/docs"] # Preview is on :3003/docs/. Displayed title is "Dev Server".
   - { port: 3004, title: "Dev Server" } # Preview is on :3004/. Displayed title is "Dev Server".