text: Title: Fix "&gt;" instead of ">" on "concepts" documentation page
  Body: On https://slack.dev/bolt-python/concepts at line 12 of "Example with AWS Lambda" there is "\&gt;" displayed, instead of ">" symbol. To fix this you have to remove "\<span class="p">;\</span>" after it
  
  ### Category (place an `x` in each of the `[ ]`)
  
  * [ ] **slack_bolt.App** and/or its core components
  * [ ] **slack_bolt.async_app.AsyncApp** and/or its core components
  * [ ] Adapters in **slack_bolt.adapter**
  * [x] Others