Add tooltip for fork numbers

[koppor]

When browsing the up-for-grabs web site, one sees a pull request icon and a number after it. It is not clear, what this number means.

Propposal: Add a tool tip on hover (and maybe keep the mouse pointer as pointer - and not change it to a text cursor)

[PushpRatan]

I have fixed this issue, this is my first contribution. Please guide me if something is wrong. Thank you.

[llr3v0ll]

I've opened a pull request for this issue