Move lsp config to local file structure

.config/nvim/lsp/systemd_lsp.lua

@@ -0,0 +1,20 @@
+---@brief
+---
+--- https://github.com/JFryy/systemd-lsp
+---
+--- A Language Server Protocol (LSP) implementation for Systemd unit files,
+--- providing editing support with syntax highlighting,
+--- diagnostics, autocompletion, and documentation.
+---
+--- `systemd-lsp` can be installed via `cargo`:
+--- ```sh
+--- cargo install systemd-lsp
+--- ```
+---
+--- A language server implementation for Systemd unit files made in Rust.
+
+---@type vim.lsp.Config
+return {
+  cmd = { 'systemd-lsp' },
+  filetypes = { 'systemd' },
+}