added FAQ (#6567)

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## PR-Codex overview
This PR introduces new details to the `page.mdx` file, providing guidance on how to enhance the performance of the `Nebula` character and improve its responses.

### Detailed summary
- Added a section on how to make `Nebula` play a certain character better, including:
  - Defining the role clearly.
  - Avoiding personality traits in responses.
  - Setting output expectations.
  - Preloading context for specific domains.
  - Utilizing session handling features.

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Author: saminacodes

apps/portal/src/app/nebula/faqs/page.mdx

@@ -20,6 +20,24 @@ Nebula supports reading and writing capabilities on any EVM-compatible chain. [V
 Yes, you may ask Nebula questions in any spoken language.
 </Details>
 
+<Details summary="How can I make Nebula play a certain character better?"> 
+1. Define the Role Clearly: Specify the character’s role and behavior in your prompt. 
+    
+    Example, “You are an assistant embedded in a blockchain application, designed to provide insights and execute transactions without introducing yourself.”
+
+2. Avoid phrases that suggest personality traits or self-awareness: Use Contextual Instructions and add specific instructions to avoid unnecessary introductions.
+
+    Example, “Respond directly to queries without stating your identity or greeting users.”
+
+3. Set Output Expectations: Guide the format of responses.
+
+    Example, “Provide concise answers or actions based on the user’s input without additional commentary.”
+
+4. Preload Context: Use Nebula’s context filters to scope responses within a specific domain (e.g., blockchain data or transactions) and avoid generic replies.
+
+5. Session Handling: Utilize Nebula’s session handling feature to maintain relevant context throughout interactions, ensuring responses align with the established character behavior.
+</Details>
+
 <Details summary="How can I improve upon Nebula's responses?"> 
 We recommend using [context filters](/nebula/key-concepts/context-filters) to improve relevant responses. You may also modify hyperparameters such as temperature, top-p, 
 and more using the OpenAI API. Learn more about our [OpenAI API integration](/nebula/plugins/openai).