docs: clarify fork-to-main repository contribution workflow for external contributors

[Copilot]

Problem

External contributors working from forks often struggle to understand how to contribute their changes back to the main repository. The existing CONTRIBUTING.md file assumed users were working directly in the main repository and didn't clearly distinguish between:

• The main repository (aws/aws-toolkit-jetbrains) where issues and PRs should be submitted
• Personal forks where development work is done
• The proper workflow from fork → pull request → main repository

This confusion was evident in questions like "how do i contribut this to the min project what are the next steps".

Solution

Enhanced the CONTRIBUTING.md file with:

1. Quick Start Section for External Contributors

Added a prominent section at the beginning that immediately clarifies:

• Main repository vs. fork distinction
• Complete contribution flow visualization
• Important note about where to create pull requests

2. Enhanced Pull Request Workflow

Replaced generic instructions with explicit step-by-step guidance including:

• Specific git commands for cloning, branching, committing, and pushing
• Clear repository URLs for each step
• Emphasis on creating PRs from fork to main repository

3. Clarified Repository References

Updated sections throughout to explicitly mention when actions should be taken in the main repository vs. personal forks, particularly for:

• Issue reporting (main repository only)
• Finding help wanted issues (main repository)
• Pull request submission (from fork to main)

4. Visual Improvements

Added emoji indicators (📝 📍) and bold formatting to highlight critical information that contributors commonly miss.

Impact

External contributors now have unambiguous guidance on:

• Where to report issues and find tasks to work on
• How to properly set up their development environment from a fork
• The complete workflow from making changes to submitting a pull request
• Which repository URLs to use for each step of the process

This addresses the common confusion point that prevents external contributors from successfully participating in the project.

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.