Add prompting tips to the help guide

### What feature do you want to see added?

Add a section to the help guide with some tips on how to craft a prompt. Include what the prompt should/shouldn't include, and what to do if generation fails.

### Why do you want this feature? Does it solve a problem?

Feedback indicates that users would value additional guidance on how to craft prompts.

### How should the feature be implemented?

In the exisitng help guide, likely on an existing page.

Also make the link to the help guide on the create page clear that the user can access prompt support.

Consider if prompt guidance for updating a prototype could also be added.

### Additional context (if applicable)

_No response_

Start by locating the existing help guide and the create page source, then inspect how the current help link is presented. Add prompt-writing guidance covering what to include or avoid and what to do when generation fails; consider whether updating prototypes also needs guidance, and verify the help link clearly offers prompt support.

Written by the indexing model from the issue text.