Improve documentation

[niranjanghule]

Hi,

I was reading through section "How Do I Get Started?" on homepage. The section mentions to read 10 reasons for using spock but doesn't provide any link/reference.
I checked the documentation but couldn't find it.
It would help reader if you attach a link or remove it if not required.

[szpak]

I don't know "10 reasons..." neighter, but one can always read my own 7 reasons ;-) (unfortunately, slightly outdated in some points, but they could be updated if needed).

[leonard84]

It refers to https://github.com/spockframework/spock/wiki/10-Reasons-to-use-Spock
The missing link has been added to the website.