[Docs] Update default scanned files to be mere readable

## Describe the change

Right now the default scanned files looks like this:

Default scanned file types: .ts, .js, jsx, tsx, vue, .mjs, .cjs, .svelte

It is correct, but we should make it more readable

## What to change

https://github.com/Chrilleweb/dotenv-diff/blob/main/docs/index.md

line 65, make the default scanned types more readable 
