docs: Mention Emacs client (#378)

Author: jcs090218

docs/index.md

@@ -64,6 +64,10 @@ The language server is available on the [VSCode Marketplace](https://marketplace
 
 You will have to install `nvim-lspconfig`, and follow the [instructions](https://github.com/neovim/nvim-lspconfig/blob/master/doc/configs.md#postgres_lsp).
 
+### Emacs
+
+The language client is available through [lsp-mode](https://github.com/emacs-lsp/lsp-mode). For more details, refer to their [manual page](https://emacs-lsp.github.io/lsp-mode/page/lsp-postgres/).
+
 ### Zed
 
 The language server is available as an Extension. It's published from [this repo](https://github.com/LoamStudios/zed-postgres-language-server).