.vimrc: Source vimrc from Neovim config

.vimrc

@@ -41,7 +41,10 @@ syntax on
 "
 " Set the filetype based on the file's extension, but only if
 " 'filetype' has not already been set
-au BufRead,BufNewFile *.config setfiletype conf
+augroup filetypedetect
+    au BufRead,BufNewFile .i3initrc set filetype=sh
+    au BufRead,BufNewFile *.config setfiletype conf
+augroup END
 
 set tabstop=4 " show existing tab with 4 spaces width
 set shiftwidth=4 " when indenting with '>', use 4 spaces width