Move lsp config to local file structure

.config/nvim/lsp/lelwel_ls.lua

@@ -0,0 +1,17 @@
+---@brief
+---
+--- https://github.com/0x2a-42/lelwel
+---
+--- Language server for lelwel grammars.
+---
+--- You can install `lelwel-ls` via cargo:
+--- ```sh
+--- cargo install --features="lsp" lelwel
+--- ```
+
+---@type vim.lsp.Config
+return {
+  cmd = { 'lelwel-ls' },
+  filetypes = { 'llw' },
+  root_markers = { '.git' },
+}