vim: Enable ftplugins at the very end

Fix error that the highlighting group 'zshOption' does not exist when
editing zsh files. I guess this is the case since ftplugins were loaded
before syntax was enabled.

.config/vim/vimrc.d/20-plugins.vim

@@ -29,6 +29,3 @@ nmap <leader>t :Tags<CR>
 let g:surround_no_mappings = 1
 packadd! vim-surround
 source $XDG_CONFIG_HOME/vim/vim-surround.vim
-
-" Load filetype plugins
-filetype plugin indent on

.config/vim/vimrc.d/90-ftplugin.vim

@@ -0,0 +1,2 @@
+" Load filetype plugins
+filetype plugin indent on