Update .CONTRIBUTING/.CONTRIBUTING.md

Co-authored-by: Bruno Galvao <[email protected]>

Author: todortodorovic

.CONTRIBUTING/.CONTRIBUTING.md

@@ -1,5 +1,19 @@
 # Contribute to the Polkadot Developer Docs
 
+## Contents
+
+- [Contributing to Polkadot Documentation](#contributing-to-polkadot-documentation)
+  - [Quick Start for Contributors](#quick-start-for-contributors)
+  - [Types of Contributions](#types-of-contributions)
+  - [Contribution Workflow](#contribution-workflow)
+  - [Run Polkadot Docs Locally](#run-polkadot-docs-locally)
+  - [Adding New Pages](#adding-new-pages)
+    - [Adding Pages to Existing Section](#adding-pages-to-existing-section)
+  - [Modifying Existing Pages](#modifying-existing-pages)
+  - [Adding Code and Text Snippets](#adding-code-and-text-snippets)
+  - [Adding Images](#adding-images)
+  - [Search Engine Optimization (SEO)](#search-engine-optimization-seo)
+  
 ## Quick Start for Contributors
 
 **New to contributing?** Start here: