docs: adds a guide for contributors

CONTRIBUTING.md

@@ -0,0 +1,11 @@
+# Contributing to Open SWE
+
+Thank you for your interest in contributing to Open SWE! This guide will help you get started.
+
+### Setup Steps
+
+1. **Fork and clone** the repository:
+   ```bash
+   git clone https://github.com/<your_username>/open-swe.git
+   cd open-swe
+   ```