add vim +PlugInstall +qall

Author: kingofctrl

README.md

@@ -191,15 +191,15 @@ Add the following line to your .vimrc.
 
     Plug 'klen/python-mode', { 'for': 'python' }
 
-Install Plugins `vim +PlugInstall +qall`
+Install Plugin `vim +PlugInstall +qall`
 
 #### Using vim as a Go IDE
 
 Add the following line to your .vimrc.
 
     Plug 'fatih/vim-go', { 'for': 'go' }
 
-Install Plugins `vim +PlugInstall +qall`
+Install Plugin `vim +PlugInstall +qall`
 
 FAQ
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