Some improvements to the contributing guide (#189)

Author: aaronpowell

CONTRIBUTING.md

@@ -9,12 +9,16 @@ Thank you for your interest in contributing to the Awesome GitHub Copilot reposi
 Instructions help customize GitHub Copilot's behavior for specific technologies, coding practices, or domains.
 
 1. **Create your instruction file**: Add a new `.md` file in the `instructions/` directory
-2. **Follow the naming convention**: Use descriptive, lowercase filenames with hyphens (e.g., `python-django.md`)
+2. **Follow the naming convention**: Use descriptive, lowercase filenames with hyphens (e.g., `python-django.instructions.md`)
 3. **Structure your content**: Start with a clear heading and organize your instructions logically
 4. **Test your instructions**: Make sure your instructions work well with GitHub Copilot
 
 #### Example instruction format:
 ```markdown
+---
+description: 'Instructions for customizing GitHub Copilot behavior for specific technologies and practices'
+---
+
 # Your Technology/Framework Name
 
 ## Instructions
@@ -40,9 +44,9 @@ Prompts are ready-to-use templates for specific development scenarios and tasks.
 #### Example prompt format:
 ```markdown
 ---
-mode: "agent"
-tools: ["codebase", "terminalCommand"]
-description: "Brief description of what this prompt does"
+mode: 'agent'
+tools: ['codebase', 'terminalCommand']
+description: 'Brief description of what this prompt does'
 ---
 
 # Prompt Title
@@ -55,6 +59,47 @@ Your goal is to...
 - Include examples where helpful
 ```
 
+### Adding Chat Modes
+
+Chat modes are specialized configurations that transform GitHub Copilot Chat into domain-specific assistants or personas for particular development scenarios.
+
+1. **Create your chat mode file**: Add a new `.chatmode.md` file in the `chatmodes/` directory
+2. **Follow the naming convention**: Use descriptive, lowercase filenames with hyphens and the `.chatmode.md` extension (e.g., `react-performance-expert.chatmode.md`)
+3. **Include frontmatter**: Add metadata at the top of your file with required fields
+4. **Define the persona**: Create a clear identity and expertise area for the chat mode
+5. **Test your chat mode**: Ensure the chat mode provides helpful, accurate responses in its domain
+
+#### Example chat mode format:
+```markdown
+---
+description: 'Brief description of the chat mode and its purpose'
+model: 'gpt-5'
+tools: ['codebase', 'terminalCommand']
+---
+
+# Chat Mode Title
+
+You are an expert [domain/role] with deep knowledge in [specific areas].
+
+## Your Expertise
+
+- [Specific skill 1]
+- [Specific skill 2]
+- [Specific skill 3]
+
+## Your Approach
+
+- [How you help users]
+- [Your communication style]
+- [What you prioritize]
+
+## Guidelines
+
+- [Specific instructions for responses]
+- [Constraints or limitations]
+- [Best practices to follow]
+```
+
 ## Submitting Your Contribution
 
 1. **Fork this repository**
@@ -68,13 +113,37 @@ Your goal is to...
    - A brief description of what your instruction/prompt does
    - Any relevant context or usage notes
 
+## What We Accept
+
+We welcome contributions covering any technology, framework, or development practice that helps developers work more effectively with GitHub Copilot. This includes:
+
+- Programming languages and frameworks
+- Development methodologies and best practices
+- Architecture patterns and design principles
+- Testing strategies and quality assurance
+- DevOps and deployment practices
+- Accessibility and inclusive design
+- Performance optimization techniques
+
+## What We Don't Accept
+
+To maintain a safe, responsible, and constructive community, we will **not accept** contributions that:
+
+- **Violate Responsible AI Principles**: Content that attempts to circumvent Microsoft/GitHub's Responsible AI guidelines or promotes harmful AI usage
+- **Compromise Security**: Instructions designed to bypass security policies, exploit vulnerabilities, or weaken system security
+- **Enable Malicious Activities**: Content intended to harm other systems, users, or organizations
+- **Exploit Weaknesses**: Instructions that take advantage of vulnerabilities in other platforms or services
+- **Promote Harmful Content**: Guidance that could lead to the creation of harmful, discriminatory, or inappropriate content
+- **Circumvent Platform Policies**: Attempts to work around GitHub, Microsoft, or other platform terms of service
+
 ## Quality Guidelines
 
 - **Be specific**: Generic instructions are less helpful than specific, actionable guidance
 - **Test your content**: Ensure your instructions or prompts work well with GitHub Copilot
 - **Follow conventions**: Use consistent formatting and naming
 - **Keep it focused**: Each file should address a specific technology, framework, or use case
 - **Write clearly**: Use simple, direct language
+- **Promote best practices**: Encourage secure, maintainable, and ethical development practices
 
 ## Code of Conduct