README.md: add Emacs as an available client

Author: John Ciolfi

README.md

@@ -21,6 +21,7 @@ MATLAB language server implements several Language Server Protocol features and
 
 ## Clients
 MATLAB language server supports these editors by installing the corresponding extension:
+* Emacs - [Emacs-MATLAB-Mode](https://github.com/mathworks/Emacs-MATLAB-Mode)
 * Neovim — [nvim-lspconfig](https://github.com/neovim/nvim-lspconfig)
 * Visual Studio® Code — [MATLAB extension for Visual Studio Code](https://github.com/mathworks/MATLAB-extension-for-vscode)