Update README

Chane repository url to https.

Signed-off-by: Martin Abente Lahaye <tch@sugarlabs.org>
Change URL field label

Replace hostname for proper URL label.

Signed-off-by: Martin Abente Lahaye <tch@sugarlabs.org>
Fix weird characters

Use negative look-around to remove weird
characters.

Signed-off-by: Martin Abente Lahaye <tch@sugarlabs.org>