Document database default changes

CHANGELOG.md

@@ -35,6 +35,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 - Rate limiter is now disabled for localhost/socket (unless remoteip plug is enabled)
 - Logger: default log level changed from `warn` to `info`.
 - Config mix task `migrate_to_db` truncates `config` table before migrating the config file.
+- Default to `prepare: :unnamed` in the database configuration.
 <details>
   <summary>API Changes</summary>
 

docs/installation/otp_en.md

@@ -73,6 +73,15 @@ rc-service postgresql restart
 systemctl restart postgresql
 ```
 
+If you are using PostgreSQL 12 or higher, add this to your Ecto database configuration
+
+```elixir
+prepare: :named,
+parameters: [
+  plan_cache_mode: "force_custom_plan"
+]
+```
+
 ### Installing Pleroma
 ```sh
 # Create a Pleroma user