docs: clarify on_attach example, quick start (#2165)

* doc: more on_attach examples

* doc: human readable mappings help

* doc: human readable mappings help

* doc: more on_attach examples

* doc: enhance quick start

* doc: enhance quick start

* doc: enhance quick start

* doc: enhance quick start

* doc: enhance quick start

* doc: enhance quick start

README.md

@@ -44,13 +44,11 @@ Please install via your preferred package manager. See [Installation](https://gi
 
 `nvim-tree/nvim-web-devicons` optional, for file icons
 
-## Setup
+## Quick Start
 
-Setup should be run in a lua file or in a lua heredoc [:help lua-heredoc](https://neovim.io/doc/user/lua.html) if using in a vim file.
+Setup the plugin in your `init.lua`
 
 ```lua
--- examples for your init.lua
-
 -- disable netrw at the very start of your init.lua (strongly advised)
 vim.g.loaded_netrw = 1
 vim.g.loaded_netrwPlugin = 1
@@ -64,6 +62,9 @@ require("nvim-tree").setup()
 -- OR setup with some options
 require("nvim-tree").setup({
   sort_by = "case_sensitive",
+  view = {
+    width = 30,
+  },
   renderer = {
     group_empty = true,
   },
@@ -73,6 +74,10 @@ require("nvim-tree").setup({
 })
 ```
 
+Open the tree:  `:NvimTreeOpen`
+
+Show the mappings:  `g?`
+
 For complete list of available configuration options see [:help nvim-tree-setup](doc/nvim-tree-lua.txt)
 
 Each option is documented in `:help nvim-tree.OPTION_NAME`. Nested options can be accessed by appending `.`, for example [:help nvim-tree.filters.dotfiles](doc/nvim-tree-lua.txt)