feat: add syntax highlighters to tools section (#249)

Author: theseion

content/6-development/6-6-useful_tools.md

@@ -72,4 +72,14 @@ A tool for testing and finding regular expressions that are vulnerable to regula
 
 https://crsdoc.digitalwave.hu
 
-Presents CRS rules using a structured UI, allowing for filtering and searching.
+Presents CRS rules using a structured UI, allowing for filtering and searching.
+
+## Syntax Highlighters
+
+### Regex Assembly
+
+We have a syntax highlighting extension for Visual Studio Code that helps with writing assembly files. Instructions on how to install the extension can be found in the readme of the repository: https://github.com/coreruleset/regexp-assemble-syntax.
+
+### ModSecurity SecLang
+
+A community member has created an experimental syntax highlighter extension for the ModSecurity SecLang for Visual Studio Code. It has a nice documentation feature for syntax elements and variables. Both highlighting and documentation have been generated using GPT-5, so expect some issues and inaccuracies. https://github.com/louis-lau/vscode-secrule-language-plugin.