docs(idempotency): tidy up doc before release (#309)

* docs: refresh doc navigation and some initial tidy up

* docs: mention built-in jmespath functions are also available

* docs: add initial example of custom persistence layer

* docs: emphasize about serialization and hashing, reorder exception handling

Author: heitorlessa

aws_lambda_powertools/utilities/idempotency/idempotency.py

@@ -46,7 +46,7 @@ def idempotent(
     persistence_store: BasePersistenceLayer
         Instance of BasePersistenceLayer to store data
     config: IdempotencyConfig
-        Configutation
+        Configuration
 
     Examples
     --------