Move lsp config to local file structure

.config/nvim/lsp/syntax_tree.lua

@@ -0,0 +1,21 @@
+---@brief
+---
+--- https://ruby-syntax-tree.github.io/syntax_tree/
+---
+--- A fast Ruby parser and formatter.
+---
+--- Syntax Tree is a suite of tools built on top of the internal CRuby parser. It
+--- provides the ability to generate a syntax tree from source, as well as the
+--- tools necessary to inspect and manipulate that syntax tree. It can be used to
+--- build formatters, linters, language servers, and more.
+---
+--- ```sh
+--- gem install syntax_tree
+--- ```
+
+---@type vim.lsp.Config
+return {
+  cmd = { 'stree', 'lsp' },
+  filetypes = { 'ruby' },
+  root_markers = { '.streerc', 'Gemfile', '.git' },
+}