docs: add contributing guidelines

CONTRIBUTING.md

@@ -0,0 +1,73 @@
+# Contributing
+
+Thank you for your interest in contributing to DebugProbe.AspNetCore.
+
+## Getting Started
+
+Clone the repository and open the solution:
+
+```bash
+git clone https://github.com/georgidhristov/DebugProbe.AspNetCore.git
+```
+
+Open:
+
+```text
+DebugProbe.AspNetCore.sln
+```
+
+## Running the Project
+
+`DebugProbe.AspNetCore` is the core class library.
+
+Use the sample application for local development and testing:
+
+```text
+DebugProbe.SampleApi/
+```
+
+Run the sample API project to test DebugProbe functionality and UI behavior during development.
+
+## Branch Naming
+
+Use descriptive lowercase branch names:
+
+Example:
+
+```text
+feature/add-request-filtering
+```
+
+## Pull Requests
+
+Before opening a pull request:
+
+- Ensure the project builds successfully
+- Keep pull requests focused and small
+- Provide a clear description of the change
+- Link related issues when applicable
+
+## Coding Style
+
+- Keep implementations simple and maintainable
+- Prefer readable code over unnecessary abstraction
+- Follow existing project structure and naming conventions
+
+## Reporting Issues
+
+When opening issues, include:
+
+- Expected behavior
+- Actual behavior
+- Steps to reproduce
+- Screenshots or logs if relevant
+
+## Security
+
+Please do not report security vulnerabilities publicly.
+
+See:
+
+```text
+SECURITY.md
+```