docs: Update memoization.md (argoproj#10992)

Signed-off-by: Adam Eri <adam.eri@blackmirror.media>
Co-authored-by: Yuan Tang <terrytangyuan@gmail.com>

docs/memoization.md

@@ -15,8 +15,9 @@ This allows you to easily manipulate cache entries manually through `kubectl` an
 
 ## Using Memoization
 
-Memoization is set at the template level. You must specify a key, which can be static strings but more often depend on inputs.
-You must also specify a name for the config-map cache.
+Memoization is set at the template level. You must specify a `key`, which can be static strings but more often depend on inputs.
+You must also specify a name for the `config-map` cache.
+Optionally you can set a `maxAge` in seconds or hours (e.g. `180s`, `24h`) to define how long should it be considered valid. If an entry is older than the `maxAge`, it will be ignored.
 
 ```yaml
 apiVersion: argoproj.io/v1alpha1
@@ -29,11 +30,14 @@ spec:
       - name: whalesay
         memoize:
            key: "{{inputs.parameters.message}}"
+           maxAge: "10s"
            cache:
               configMap:
                  name: whalesay-cache
 ```
 
+[Find a simple example for memoization here](https://github.com/argoproj/argo-workflows/blob/master/examples/memoize-simple.yaml).
+
 !!! Note
     In order to use memoization it is necessary to add the verbs `create` and `update` to the `configmaps` resource for the appropriate (cluster) roles. In the case of a cluster install the `argo-cluster-role` cluster role should be updated, whilst for a namespace install the `argo-role` role should be updated.