Add memcached app doc

Signed-off-by: yunkunrao <yunkunrao@yunify.com>

content/en/docs/application-store/built-in-apps/memcached-app.md

@@ -0,0 +1,34 @@
+---
+title: "Memcached App"
+keywords: 'Kubernetes, KubeSphere, Memcached, app-store'
+description: 'How to use built-in Memcached Object Storage'
+
+
+weight: 2242
+---
+Memcached is designed for large data caches. Its API is available for most popular languages. This guide will show you one-click deployment for Memcached in Kubenetes .
+
+## Prerequisites
+
+- You have enabled [KubeSphere App Store](../../pluggable-components/app-store)
+- You have completed the tutorial in [Create Workspace, Project, Account and Role](../../quick-start/create-workspace-and-project/). Now switch to use `project-regular` account to log in and enter into `demo-peoject`.
+
+## Hands-on Lab
+
+### Common steps
+
+1. Choose Memcached template `From App Store`.
+
+![choose_memcached_from_app_store](/images/docs/appstore/memcached/choose_memcached_from_app_store.png)
+
+2. Check app info and click `Deploy` button.
+
+![deploy_minio](/images/docs/appstore/memcached/deploy_memcached.png)
+
+3. Select app version and deployment location, then go to **Next → Deploy**
+
+![deploy_memcached_confirm](/images/docs/appstore/memcached/deploy_memcached_confirm.png)
+
+4. Wait for a few minutes, then you will see the application memcached showing active on the application list.
+
+![minio_active](/images/docs/appstore/memcached/memcached_active.png)