Create a Slack welcome app

[egiurleo]

Is your feature request related to a problem? Please describe.
Currently, we don't do a good job of welcoming new members to the WNB.rb Slack community. There are too many new people joining to greet them individually, which means we miss out on a crucial opportunity to make new members feel welcome and supported.

Describe the solution you'd like
I have written a document introducing new members to the WNB.rb Slack workspace. I would like this document to be automatically sent to anyone who joins the WNB.rb Slack workspace by a Slack bot.

Why don't we just use Slack Workflows?
Workflows are a paid feature and it's not financially feasible for WNB.rb to pay for Slack right now.

Desired Approach

• I have already created a new Slack app that we can use to send messages to users. Please reach out to me on WNB.rb Slack so I can share the credentials with you.
• Follow this tutorial for using the Slack Events API
  • Basically, you'll create a new endpoint that the Slack app will ping every time a new user joins our workspace; you'll have to follow the guidelines in the tutorial above to make sure that endpoint responds appropriately to Slack event requests.
  • The event will trigger a message from the Slack app to the new user (probably using the slack-ruby-client)

This is a fairly significant piece of work that will require some previous knowledge of Rails API endpoints, requests, and responses.