docs: update README

Author: joker1007

Diff for: README.md

@@ -1,35 +1,13 @@
 # tree-sitter-rbs
 
+[![Build/test](https://github.com/joker1007/tree-sitter-rbs/actions/workflows/ci.yml/badge.svg)](https://github.com/joker1007/tree-sitter-rbs/actions/workflows/ci.yml)
+
 [rbs](https://github.com/ruby/rbs) grammar for [tree-sitter](https://github.com/tree-sitter/tree-sitter).
 
 syntax reference is https://github.com/ruby/rbs/blob/master/docs/syntax.md
 
 ## Use this in Neovim
 
-1. add following code to install parser manually.
-
-```lua
-local parser_config = require("nvim-treesitter.parsers").get_parser_configs()
-parser_config.rbs = {
-  install_info = {
-    url = "https://github.com/joker1007/tree-sitter-rbs",
-    files = { "src/parser.c" },
-    branch = "main",
-  },
-  filetype = "rbs",
-}
-```
-
-2. run `:TSInstall rbs`
-
-3. install this repository as a neovim plugin
-
-```lua
--- lazy.nvim
-require("lazy").setup({
-  "joker1007/tree-sitter-rbs"
-})
+this parser is supported in nvim-treesitter. (https://github.com/nvim-treesitter/nvim-treesitter/pull/5745)
 
--- packer.nvim
-use { "joker1007/tree-sitter-rbs" }
-```
+Please run `:TSInstall rbs`