Update README with redis eviction notes (#1298)

README has been updated with appropriate notes on redis eviction
considerations.

Author: jaymell

README.md

@@ -180,7 +180,14 @@ If you already have one, you just need to run `cargo build`, otherwise, please p
 The server requires the following runtime dependencies to work correctly:
 
 - A PostgreSQL server - for the storage of events.
-- An *optional* Redis server version 6.2.0 or higher - for the task queue and cache. Please note that it's recommended to enable persistence in Redis so that tasks are persisted across Redis server restarts and upgrades.
+- An *optional* Redis server version 6.2.0 or higher - for the task queue and cache.
+
+## Redis/Valkey Considerations
+### Persistence
+Please note that it's recommended to enable persistence in Redis so that tasks are persisted across Redis server restarts and upgrades.
+
+### Eviction Policy
+Please ensure that your Redis instances are configured to not evict keys without explicit `expire` policies set. This means that `maxmemory-policy` should be set to `noeviction` or to any of the available `volatile-` policies. See Redis/Valkey documentation for further information.
 
 ## Server configuration