neovim: Add cosco-vim

I tried this for a few days and although the auto-semicolons were cool,
they'd sometimes get in the way. I haven't used the keybind much at all
however, so I may remove this in the future.

home/neovim.nix

@@ -170,6 +170,7 @@ in
       nnoremap <silent> <leader>; :NvimTreeToggle<CR>
       nnoremap <silent> <leader>z :ZenMode<CR>
       nnoremap <silent> <leader>b :TagbarToggle<CR>
+      nnoremap <silent> <leader>' :CommaOrSemiColon<CR>
       vnoremap <C-s> y:silent !notify-send -t 4000 "成果" "$(tango '<C-r>0')"<CR>:<Esc>
 
       autocmd BufNewFile,BufRead *.ecr    setlocal syntax=html
@@ -542,6 +543,7 @@ in
           require('nvim-ts-autotag').setup()
         '';
       }
+      cosco-vim
       fzf-vim
       vim-caddyfile
       vim-graphql