Re: Make all tree-sitter modes optional

[Yuan Fu]

> 
> The userbase I'm familiar with has been messing with auto-mode-alist for 
> decades. To make it easier, people have been adding the necessary lines to 
> documentation: either to the repository's README, or to package's Commentary. 
> So the user could take it from there.
> 
> Similarly, we can add such line to the Commentary of every ts mode, or even 
> to the major mode docstrings

IF we do that, it’d be better to instruct users to use major-mode-remap-alist, 
since it’s easier to understand and use IMO.

Yuan