docs: add ephemeral storage documentation (#2240)

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site/content/docs/include/common-svc-fields.md

@@ -137,7 +137,29 @@ Key-value pairs that represent secret values from [AWS Systems Manager Parameter
 <div class="separator"></div>  
 
 <a id="storage" href="#storage" class="field">`storage`</a> <span class="type">Map</span>  
-The Storage section lets you specify external EFS volumes for your containers and sidecars to mount. This allows you to access persistent storage across regions for data processing or CMS workloads. For more detail, see the [storage](../developing/storage.en.md) page.
+The Storage section lets you specify external EFS volumes for your containers and sidecars to mount. This allows you to access persistent storage across regions for data processing or CMS workloads. For more detail, see the [storage](../developing/storage.en.md) page. You can also specify extensible ephemeral storage at the task level.
+
+<span class="parent-field">storage.</span><a id="ephemeral" href="#ephemeral" class="field">`ephemeral`</a> <span class="type">Int</span>
+Specify how much ephemeral task storage to provision in GiB. The default value and minimum is 20 GiB. The maximum size is 200 GiB. Sizes above 20 GiB incur additional charges.
+
+To create a shared filesystem context between an essential container and a sidecar, you can use an empty volume:
+```yaml
+storage:
+  ephemeral: 100
+  volumes:
+    scratch:
+      path: /var/data
+      read_only: false
+
+sidecars:
+  mySidecar:
+    image: public.ecr.aws/my-image:latest
+    mount_points:
+      - source_volume: scratch
+        path: /var/data
+        read_only: false
+```
+This example will provision 100 GiB of storage to be shared between the sidecar and the task container. This can be useful for large datasets, or for using a sidecar to transfer data from EFS into task storage for workloads with high disk I/O requirements.
 
 <span class="parent-field">storage.</span><a id="volumes" href="#volumes" class="field">`volumes`</a> <span class="type">Map</span>  
 Specify the name and configuration of any EFS volumes you would like to attach. The `volumes` field is specified as a map of the form:
@@ -155,10 +177,10 @@ Specify the configuration of a volume.
 <span class="parent-field">volume.</span><a id="path" href="#path" class="field">`path`</a> <span class="type">String</span>  
 Required. Specify the location in the container where you would like your volume to be mounted. Must be fewer than 242 characters and must consist only of the characters `a-zA-Z0-9.-_/`.
 
-<span class="parent-field">volume.</span><a id="read_only" href="#read-only" class="field">`read_only`</a> <span class="type">Bool</span>  
+<span class="parent-field">volume.</span><a id="read_only" href="#read-only" class="field">`read_only`</a> <span class="type">Boolean</span>  
 Optional. Defaults to `true`. Defines whether the volume is read-only or not. If false, the container is granted `elasticfilesystem:ClientWrite` permissions to the filesystem and the volume is writable.
 
-<span class="parent-field">volume.</span><a id="efs" href="#efs" class="field">`efs`</a> <span class="type">Bool or Map</span>  
+<span class="parent-field">volume.</span><a id="efs" href="#efs" class="field">`efs`</a> <span class="type">Boolean or Map</span>  
 Specify more detailed EFS configuration. If specified as a boolean, or using only the `uid` and `gid` subfields, creates a managed EFS filesystem and dedicated Access Point for this workload.
 ```yaml
 // Simple managed EFS
@@ -185,7 +207,7 @@ Optional. Must be specified with `uid`. Mutually exclusive with `root_dir`, `aut
 <span class="parent-field">volume.efs.</span><a id="auth" href="#auth" class="field">`auth`</a> <span class="type">Map</span>  
 Specify advanced authorization configuration for EFS.
 
-<span class="parent-field">volume.efs.auth.</span><a id="iam" href="#iam" class="field">`iam`</a> <span class="type">Bool</span>  
+<span class="parent-field">volume.efs.auth.</span><a id="iam" href="#iam" class="field">`iam`</a> <span class="type">Boolean</span>  
 Optional. Defaults to `true`. Whether or not to use IAM authorization to determine whether the volume is allowed to connect to EFS.
 
 <span class="parent-field">volume.efs.auth.</span><a id="access_point_id" href="#access-point-id" class="field">`access_point_id`</a> <span class="type">String</span>