Make popular integrations (e.g. chat, Slack) easier to find

[reichert621]

Problem
The most common use case for Papercups is setting up chat + reply from Slack.

We should make these two integration settings super easy to find and configure.

Solution

• Improve "getting started" page to include links to both of these settings
• Add "popular" badges to these rows in the integrations tables
• Add quick links to the primary inbox integrations settings on the main integrations page

Questions, or need help getting started?
Feel free to ask below, or ping us on Slack :)

(You can also check out our CONTRIBUTING.md)