Fix YouTube branding in README

[LorenzoSapora]

Note: Your facade is currently Youtube and to be technically correct you'd probably want to change this to YouTube. But not required.

[ricardo]

@alaouy – Can you change the repository name capitalization so it's consistent with YouTube's branding?

That shouldn't affect existing links or clones because GitHub repo names are not case-sensitive.

You can quickly perform the change via https://github.com/alaouy/Youtube/settings.

[alaouy]

Thank you all for your contribution 💯