Run a "set up new bridges" campaign

We currently have around 500 obfs4 bridges. That's not a lot and some of them don't work properly, so the effective number is even lower. It's time to ask volunteers to set up more bridges.

One way to do that is by writing a blog post and doing outreach on Twitter. We should point people to our obfs4 setup guide. Ideally, we would start with a small group of people (e.g., by posting to tor-relays@), fix any issues that we discover in our guide, and then repeat the outreach campaign for a larger set of people.

Another thing worth considering is what kind of bridges we want:

• We certainly need more obfs4 bridges even though the protocol still has some UX issues for operators (see legacy/trac#30471 (moved)).
• More vanilla bridges would be useful too but, since legacy/trac#28655 (moved), only if the bridge doesn't also run an obfs4 protocol. Otherwise BridgeDB won't hand out the vanilla bridge line. As an added bonus, modern tor bridges may currently be resistant to the GFW's active probing as discussed over in legacy/trac#30500 (moved).
• Once legacy/trac#23888 (moved) is done, we should also encourage people to install the snowflake webextension.