Add stan-language-server to servers.md (#2257)

Author: WardBrian

_implementors/servers.md

@@ -253,6 +253,7 @@ index: 1
 | SPARQL | [Stardog Union](https://github.com/stardog-union) | [SPARQL Language Server](https://github.com/stardog-union/stardog-language-servers/tree/master/packages/sparql-language-server) | TypeScript |
 | [Sphinx](https://www.sphinx-doc.org/en/master/) | [Alex Carney](https://github.com/alcarney) | [esbonio](https://github.com/swyddfa/esbonio) | Python |
 | SQL | [Toshikazu Ohashi](https://github.com/lighttiger2505) | [sqls](https://github.com/lighttiger2505/sqls) | Go |
+| [Stan](https://mc-stan.org/) | [Jens Kouros](https://github.com/tomatitito) | [stan-language-server](https://github.com/tomatitito/stan-language-server) | TypeScript / OCaml |
 | Standard ML | [azdavis](https://azdavis.net) | [Millet](https://github.com/azdavis/millet) | Rust |
 | [Stimulus](https://stimulus.hotwired.dev) | [Marco Roth](https://github.com/marcoroth) | [Stimulus LSP](https://github.com/marcoroth/stimulus-lsp) | TypeScript | 
 | Stylable | [Wix.com](https://www.wix.com) | [stylable/language-service](https://github.com/wix/stylable/tree/master/packages/language-service) | TypeScript |