Writing up signals

I made an instruction page for writing up credibility signals: 
Instructions for Writing Up a Credibility Signal. 
<https://docs.google.com/document/d/1aM2oURlgMdGNvA4Zvyy4q3LkAiVkK_S5GQ_6lg73k44/edit#>

Give it a try, and let me know if you get stuck anywhere.

There are some signals eagerly awaiting write-ups at Credibility Signals 
Review Process. 
<https://docs.google.com/document/d/1i6lCJPaJLQwrDUknnzWW5ixgWb8xp54KdLu2mam206Q/edit>

       -- Sandro