Optionally use alphabetic ordering if numeric ordering is not present

[benmccann]

Description

I think it'd be nice to just display these pages alphabetically: https://github.com/sveltejs/eslint-plugin-svelte/tree/main/docs/rules

Rather than making them preprend all those pages with numbers as we've done in https://github.com/sveltejs/svelte/tree/main/documentation/docs we should just use the alphabetic ordering

We should probably see if they can adopt the numeric ordering for https://github.com/sveltejs/eslint-plugin-svelte/tree/main/docs though