docs(dashboard): Clarify migration prompt usage

docs/docs/guides/extending-the-dashboard/migration/index.md

@@ -29,15 +29,15 @@ in around 20-30 minutes.
 
 ### Full Prompt
 
-Paste this into your AI assistant and make sure to specify the plugin by path, i.e.:
+Give a prompt like this to your AI assistant and make sure to specify the plugin by path, i.e.:
 
 ```
 Migrate the plugin at @src/plugins/my-plugin/ 
 to use the new dashboard.
-
-[Pasted text #1 +1390 lines]
 ```
 
+Then paste the following prompt in full:
+
 <div style={{ width: '100%', height: '500px', overflow: 'auto' }}>
 
 <!-- Note: the following code block should not be edited. It is auto-generated from the files in the 
@@ -1540,6 +1540,10 @@ defineDashboardExtension({
 
 </div>
 
+:::tip
+The full prompt is quite large, so it can make sense to first clear the current LLM context,
+e.g. with `/clear` in Claude Code or `/new` in Codex CLI
+
 ### Claude Skills
 
 If you use Claude Code, you can use [Agent Skills](https://docs.claude.com/en/docs/agents-and-tools/agent-skills/overview) to set