docs: refresh stale snippets for holochain 0.6.1 / client 0.20.4

- dev-setup.md: bump example holochain version output to 0.6.1
- stories/3.1-frontend-setup.mdx: AppAgentWebsocket was renamed to
  AppWebsocket in @holochain/client; update the setup snippet so it
  compiles against 0.20.4

Author: zippy

dev-setup.md

@@ -21,7 +21,7 @@ holochain --version
 Should give something like:
 
 ```bash
-holochain 0.1.3
+holochain 0.6.1
 ```
 
 ## Install

stories/3.1-frontend-setup.mdx

@@ -26,10 +26,10 @@ npm install @holochain-open-dev/profiles -w ui
 
 ```js
 import { ProfilesStore, ProfilesClient } from "@holochain-open-dev/profiles";
-import { AppWebsocket, AppAgentWebsocket } from "@holochain/client";
+import { AppWebsocket } from "@holochain/client";
 
 async function setupProfilesStore() {
-  const client = await AppAgentWebsocket.connect('', '')
+  const client = await AppWebsocket.connect()
 
 // TODO: change "MY_CELL_ROLE" for the roleId that you can find in your "happ.yaml"
   const profilesStore = new ProfilesStore(new ProfilesClient(client, '<MY_CELL_ROLE>'), {