Document ephemeral activity changes better

Also remove the example from the cheatsheet, there is no need for it
when the types are simple

CHANGELOG.md

@@ -16,6 +16,9 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - **Breaking:** Removed `Pleroma.Workers.Cron.ClearOauthTokenWorker` setting from Oban `:crontab` config.
 - **Breaking:** Removed `Pleroma.Workers.Cron.PurgeExpiredActivitiesWorker` setting from Oban `:crontab`.
 
+### Changed
+- Minimum lifetime for ephmeral activities changed to 10 minutes and made configurable (`:min_lifetime` option).
+
 ## [2.1.1] - 2020-09-08
 
 ### Security

docs/configuration/cheatsheet.md

@@ -1092,15 +1092,9 @@ config :pleroma, :frontends,
 
 This would serve the frontend from the the folder at `$instance_static/frontends/pleroma/stable`. You have to copy the frontend into this folder yourself. You can choose the name and ref any way you like, but they will be used by mix tasks to automate installation in the future, the name referring to the project and the ref referring to a commit.
 
-## Ephemeral activities
+## Ephemeral activities (Pleroma.Workers.PurgeExpiredActivity)
 
 Settings to enable and configure expiration for ephemeral activities
 
 * `:enabled` - enables ephemeral activities creation
 * `:min_lifetime` - minimum lifetime for ephemeral activities (in seconds). Default: 10 minutes.
-
-Example:
-
-```elixir
-  config :pleroma, Pleroma.Workers.PurgeExpiredActivity, enabled: true, min_lifetime: 600
-```