Simplify the installation instruction

doc/fzf-vim.txt

@@ -77,21 +77,14 @@ fzf/Vim integration, see {README-VIM}{4}.
 
 < Using vim-plug >____________________________________________________________~
                                                         *fzf-vim-using-vim-plug*
-
-If you already installed fzf using {Homebrew}{5}, the following should
-suffice:
 >
-    Plug '/usr/local/opt/fzf'
+    Plug 'junegunn/fzf'
     Plug 'junegunn/fzf.vim'
 <
-But if you want to install fzf as well using vim-plug:
->
-    Plug 'junegunn/fzf', { 'dir': '~/.fzf', 'do': './install --all' }
-    Plug 'junegunn/fzf.vim'
-<
- - `dir` and `do` options are not mandatory
- - Use `./install --bin` instead if you don't need fzf outside of Vim
  - Make sure to use Vim 7.4 or above
+ - If you have already installed fzf using {Homebrew}{5}, and do not wish to have
+   another copy on your system, replace the first line with
+   `Plug '/usr/local/opt/fzf'`
 
                                                           {5} https://brew.sh/