[vim] Add fzf#install() for downloading fzf binary

README.md

@@ -138,39 +138,18 @@ page][windows-wiki].
 
 ### As Vim plugin
 
-Once you have fzf installed, you can enable it inside Vim simply by adding the
-directory to `&runtimepath` in your Vim configuration file. The path may
-differ depending on the package manager.
+If you use
+[vim-plug](https://github.com/junegunn/vim-plug), add this line to your Vim
+configuration file:
 
 ```vim
-" If installed using Homebrew
-set rtp+=/usr/local/opt/fzf
-
-" If installed using git
-set rtp+=~/.fzf
+Plug 'junegunn/fzf', { 'do': { -> fzf#install() } }
 ```
 
-If you use [vim-plug](https://github.com/junegunn/vim-plug), the same can be
-written as:
+`fzf#install()` makes sure that you have the latest binary, but it's optional,
+so you can omit it if you use a plugin manager that doesn't support hooks.
 
-```vim
-" If installed using Homebrew
-Plug '/usr/local/opt/fzf'
-
-" If installed using git
-Plug '~/.fzf'
-```
-
-But instead of separately installing fzf on your system (using Homebrew or
-"git clone") and enabling it on Vim (adding it to `&runtimepath`), you can use
-vim-plug to do both.
-
-```vim
-" PlugInstall and PlugUpdate will clone fzf in ~/.fzf and run the install script
-Plug 'junegunn/fzf', { 'dir': '~/.fzf', 'do': './install --all' }
-  " Both options are optional. You don't have to install fzf in ~/.fzf
-  " and you don't have to run the install script if you use fzf only in Vim.
-```
+For more installation options, see [README-VIM.md](README-VIM.md).
 
 Upgrading fzf
 -------------