[tor-project] August 2017 report for the metrics team

[Damian Johnson]

> Formalized the steps for sanitizing bridge descriptors [2] that are
> collected and published by CollecTor.
>
>  [2] https://metrics.torproject.org/bridge-descriptors.html

Neat, great stuff! Delightfully detailed. :P

One quick thing: when we next change sanitization would you mind
adding a 'changes' section with the date of the change and what the
modification was? I keep an eye on the tor-spec git changes to know
when the dir-spec changes but a webpage like this is harder to track.
A list to answer the question of "Last time I checked this was August.
Has anything changed?" would be handy.

Cheers! -Damian