Do not look for clint updates always / automatically

[blueyed]

Currently nvimdev#update_clint_errors looks for updates for https://raw.githubusercontent.com/neovim/doc/gh-pages/reports/clint/errors.json always (during startup).

This should at least only be done for when linting is used maybe, and even not automatically by default, but maybe a command - it creates a remote we request in the background, basically stamping how often you open Neovim in the Neovim project.. 8|

The update script: https://github.com/neovim/nvimdev.nvim/blob/master/scripts/download_errors.py