Add flymake-ruff to docs (#3800)

docs/editor-integrations.md

@@ -126,9 +126,59 @@ Ruff can be integrated into any editor that supports the Language Server Protoco
 (see: [Language Server Protocol](#language-server-protocol-official)), including Vim and Neovim.
 
 It's recommended that you use [`ruff-lsp`](https://github.com/charliermarsh/ruff-lsp), the
-officially supported LSP server for Ruff.
+officially supported LSP server for Ruff. To use `ruff-lsp` with Neovim, install `ruff-lsp` from
+PyPI along with [`nvim-lspconfig`](https://github.com/neovim/nvim-lspconfig). Then, add something
+like the following to your `init.lua`:
 
-However, Ruff is also available as part of the [coc-pyright](https://github.com/fannheyward/coc-pyright)
+```lua
+-- See: https://github.com/neovim/nvim-lspconfig/tree/54eb2a070a4f389b1be0f98070f81d23e2b1a715#suggested-configuration
+local opts = { noremap=true, silent=true }
+vim.keymap.set('n', '<space>e', vim.diagnostic.open_float, opts)
+vim.keymap.set('n', '[d', vim.diagnostic.goto_prev, opts)
+vim.keymap.set('n', ']d', vim.diagnostic.goto_next, opts)
+vim.keymap.set('n', '<space>q', vim.diagnostic.setloclist, opts)
+
+-- Use an on_attach function to only map the following keys
+-- after the language server attaches to the current buffer
+local on_attach = function(client, bufnr)
+  -- Enable completion triggered by <c-x><c-o>
+  vim.api.nvim_buf_set_option(bufnr, 'omnifunc', 'v:lua.vim.lsp.omnifunc')
+
+  -- Mappings.
+  -- See `:help vim.lsp.*` for documentation on any of the below functions
+  local bufopts = { noremap=true, silent=true, buffer=bufnr }
+  vim.keymap.set('n', 'gD', vim.lsp.buf.declaration, bufopts)
+  vim.keymap.set('n', 'gd', vim.lsp.buf.definition, bufopts)
+  vim.keymap.set('n', 'K', vim.lsp.buf.hover, bufopts)
+  vim.keymap.set('n', 'gi', vim.lsp.buf.implementation, bufopts)
+  vim.keymap.set('n', '<C-k>', vim.lsp.buf.signature_help, bufopts)
+  vim.keymap.set('n', '<space>wa', vim.lsp.buf.add_workspace_folder, bufopts)
+  vim.keymap.set('n', '<space>wr', vim.lsp.buf.remove_workspace_folder, bufopts)
+  vim.keymap.set('n', '<space>wl', function()
+    print(vim.inspect(vim.lsp.buf.list_workspace_folders()))
+  end, bufopts)
+  vim.keymap.set('n', '<space>D', vim.lsp.buf.type_definition, bufopts)
+  vim.keymap.set('n', '<space>rn', vim.lsp.buf.rename, bufopts)
+  vim.keymap.set('n', '<space>ca', vim.lsp.buf.code_action, bufopts)
+  vim.keymap.set('n', 'gr', vim.lsp.buf.references, bufopts)
+  vim.keymap.set('n', '<space>f', function() vim.lsp.buf.format { async = true } end, bufopts)
+end
+
+-- Configure `ruff-lsp`.
+-- See: https://github.com/neovim/nvim-lspconfig/blob/master/doc/server_configurations.md#ruff_lsp
+-- For the default config, along with instructions on how to customize the settings
+require('lspconfig').ruff_lsp.setup {
+  on_attach = on_attach,
+  init_options = {
+    settings = {
+      -- Any extra CLI arguments for `ruff` go here.
+      args = {},
+    }
+  }
+}
+```
+
+Ruff is also available as part of the [coc-pyright](https://github.com/fannheyward/coc-pyright)
 extension for `coc.nvim`.
 
 <details>
@@ -194,6 +244,15 @@ Ruff should then appear as a runnable action:
 Ruff is also available as the [Ruff](https://plugins.jetbrains.com/plugin/20574-ruff) plugin on the
 IntelliJ Marketplace (maintained by @koxudaxi).
 
+## Emacs (Unofficial)
+
+Ruff is available as [`flymake-ruff`](https://melpa.org/#/flymake-ruff) on MELPA:
+
+```elisp
+(require 'flymake-ruff)
+(add-hook 'python-mode-hook #'flymake-ruff-load)
+```
+
 ## TextMate (Unofficial)
 
 Ruff is also available via the [`textmate2-ruff-linter`](https://github.com/vigo/textmate2-ruff-linter)