Populate Slack Welcome message

[jinniw43805]

Context:
Currently, we will send the user a welcome message when user joins the Ploomber Slack Workspace.
We may consider to provide the list of our current links.

Example - Ideal After:

Example - Currently Implementation:

Action Item:

• Discuss if providing those links will help users to find the resource easier
  • What to include in the list? Currently we can have Ploomber.io, Github link, Doc link, Blog link
• Modify the bot message with the new adding section

[tonykploomber]

@idomic
Do you think it's possible to grant the permission to me to edit the Slack Bot?