cgit: linked phrases beneath the 'Clone' subheading

[Graham Perrin]

A nit.

Beneath the 'Clone' subheadings at <https://cgit.freebsd.org/doc>, 
<https://cgit.freebsd.org/ports> and <https://cgit.freebsd.org/src> the 
phrases '(public-mirror)' and '(developers-only)' are linked.

Resulting URLs such as <https://cgit.freebsd.org/(public-mirror)> may be 
a source of confusion to newcomers who find themselves at the page for 
ports.