Installation of additional plugins

[p-alik]

I've been unsuccessfully trying to install vim-stylish-haskell with regard to Customizing section.

Unfortunately it isn't obviously to me which of three mentioned file I've to use. So I sequentially used all three with the same content below:

call plug#begin('~/.vim/plugins-extra')
Plug 'git@github.com:nbouscal/vim-stylish-haskell.git'
call plug#end()

It appears to me the vim behavior is the same by using vimrc.local or plugins.vim:
:PlugInstall shows only:
- vim-stylish-haskell: Already installed

vimrc.local.pre seems to be ignored at all.
:PlugInstall shows all except vim-stylish-haskell:

- gitignore: Already installed
- vim-extradite: Already installed
- vimproc.vim: Already installed
- tslime.vim: Already installed
- nerdtree: Already installed
- hlint-refactor-vim: Already installed
- vim-indent-object: Already installed
- vim-haskellConcealPlus: Already installed
- vim-bbye: Already installed
- vim-commentary: Already installed
- vim-fugitive: Already installed
- tagbar: Already installed
- vim-mundo: Already installed
- Align: Already installed
- tabular: Already installed
- ghcmod-vim: Already installed
- neomake: Already installed
- vim-airline: Already installed
- vim-bracketed-paste: Already installed
- vim-indent-guides: Already installed
- vim-easymotion: Already installed
- wombat256.vim: Already installed
- neco-ghc: Already installed
- ctrlp.vim: Already installed
- vim-tmux-navigator: Already installed
- vim-hoogle: Already installed
- supertab: Already installed
- haskell-vim: Already installed

[p-alik]

similar issue #185