Update README.md

Add introduction of pre-build image

Author: jubilee2

README.md

@@ -5,19 +5,35 @@ and make some change for raspberry Pi
 I suggest enable the [zram](http://yulun.me/2015/enable-zram-for-raspberry-pi-debian/) to increase performance.
 
 ## Install Docker on Raspberry Pi
-```
+[official documents link](https://docs.docker.com/install/linux/docker-ce/debian/#install-using-the-convenience-script)
+```bash
 curl -sSL https://get.docker.com | sh
 ```
 
-## Build Gitlab image:
+# Install & run container
+## Method 1 use pre-build image
+```bash
+sudo docker run --detach \
+    --hostname IP \
+    --publish 443:443 --publish 80:80 --publish 22:22 \
+    --name gitlab \
+    --restart always \
+    --volume /srv/gitlab/config:/etc/gitlab \
+    --volume /srv/gitlab/logs:/var/log/gitlab \
+    --volume /srv/gitlab/data:/var/opt/gitlab \
+    jubilee2/rpi-gitlab-ce:v11.10.4
+```
+
+## Method 2 build image by your self
+### Build Gitlab image:
 ```bash
 sudo apt-get install git 
 git clone https://github.com/jubilee2/rpi-gitlab-ce.git
 cd rpi-gitlab-ce
 sudo docker build -t gitlab-ce .
 ```
 
-## Run Gitlab container:
+### Run Gitlab container:
 ```bash
 sudo docker run --detach \
     --hostname IP \
@@ -30,4 +46,9 @@ sudo docker run --detach \
     gitlab-ce:latest
 ```
 
+# Experience
+It's need 20 min for first start up on my `raspberry PI 3 B+` with enable zram
+I observe this error occurred [link](https://gitlab.com/gitlab-org/omnibus-gitlab/blob/master/doc/common_installation_problems/README.md#failed-to-modify-kernel-parameters-with-sysctl), but after several automatic restarts, the initialization was completed.
+
+
 [More Documents!](https://docs.gitlab.com/omnibus/docker/)