Update development_environment.mdx (#2503)

Author: lboue

docs/development_environment.mdx

@@ -113,7 +113,7 @@ brew install python3 autoconf ffmpeg cmake make
 
 If you encounter build issues with `cryptography` when running the `script/setup` script below, check the cryptography documentation for [installation instructions](https://cryptography.io/en/latest/installation/#building-cryptography-on-macos).
 
-## Setup Local Repository
+### Setup Local Repository
 
 Visit the [Home Assistant Core repository](https://github.com/home-assistant/core) and click **Fork**.
 Once forked, setup your local copy of the source using the commands: