fixup! fixup! docs: add contribution guide and PR description template

Author: pulsastrix

CONTRIBUTING.md

@@ -1,10 +1,10 @@
 # Contribution Guide for libcoap-rs
 
 1. [Environment Setup](#environment-setup)
-    1. [Using Nix/devenv.sh natively](#using-nix-devenv.sh-natively)
+    1. [Using Nix/devenv.sh natively](#using-nixdevenvsh-natively)
         1. [IDE Setup](#ide-setup)
     2. [Manual Environment Setup](#manual-environment-setup)
-    3. [Using Nix/devenv.sh with an IDE using devcontainers](#using-nix-devenv.sh-with-an-ide-using-devcontainers)
+    3. [Using Nix/devenv.sh with an IDE using devcontainers](#using-nixdevenvsh-with-an-ide-using-devcontainers)
 2. [Committing your Code](#committing-your-code)
 3. [Submitting a Pull Request](#submitting-a-pull-request)
     1. [General and LLM-specific Legal Considerations](#general-and-llm-specific-legal-considerations)