Docs: add global fx in the website

[goohooh]

Suggestion

⭐ Suggestion

How about adding window.fx namespace in website like lodash?

💻 Use Cases

Tests fxts functions on the browser console directly

[goohooh]

Actually, I've been working on it without asking the community first. If this proposal is approved, I'll reopen the PR

[ppeeou]

@goohooh Thank you for your interest. It's a good suggestion

We already have it available via _, so I think it would be better to try using _.
The fx name already exists. https://fxts.dev/docs/fx