Docs: Slugification strategies

Hello!

Configuration | Zola says:

Note that if you are using a strategy other than the default, you will have to manually escape whitespace and Markdown tokens to be able to link to your pages. For example an internal link to a file named some space.md will need to be written like some%20space.md in your Markdown files.

What are “Markdown tokens”? The docs give an example for whitespace but not Markdown token. Maybe we should add one for Markdown token too…