Better empty pull requests placeholder

[andrew]

The pull requests box on the homepage before December first looks a little sad, maybe we can add in some explaination of why it's empty and when it gets started?

[Roshanjossey]

@andrew, @xadamy, are we planning to handle this for the time period before December or should we put in some extra effort for the scenario where there haven't been any pull requests at the beginning of December?

[andrew]

@Roshanjossey would be good to have this before December as we'll start to see more people coming to the site at the end of November too

[Gokilp]

you cann assign me