add --vector-db option to create-llama (#473)

index.ts

@@ -132,6 +132,13 @@ const program = new Commander.Command(packageJson.name)
     `
 
   Choose an action after installation. For example, 'runApp' or 'dependencies'. The default option is just to generate the app.
+`,
+  )
+  .option(
+    "--vector-db <vectorDb>",
+    `
+
+  Select which vector database you would like to use, such as 'none', 'pg' or 'mongo'. The default option is not to use a vector database and use the local filesystem instead ('none').
 `,
   )
   .allowUnknownOption()