docker version number string added OS string
diff --git a/docs-site/docs/installation.md b/docs-site/docs/installation.md
index 72f5d30..a822019 100644
--- a/docs-site/docs/installation.md
+++ b/docs-site/docs/installation.md
@@ -66,7 +66,7 @@
1. CPU-only.
```shell
-$ docker run -it apache/singa:X.Y.Z-cpu /bin/bash
+$ docker run -it apache/singa:X.Y.Z-cpu-ubuntu16.04 /bin/bash
```
2. With GPU enabled. Install
@@ -74,7 +74,7 @@
Docker.
```shell
-$ nvidia-docker run -it apache/singa:X.Y.Z-gpu /bin/bash
+$ nvidia-docker run -it apache/singa:X.Y.Z-cuda9.0-cudnn7.4.2-ubuntu16.04 /bin/bash
```
3. For the complete list of SINGA Docker images (tags), visit the
@@ -91,6 +91,7 @@
| `cpu` | the image cannot run on GPUs | 'cpu' |
| `gpu` | the image can run on Nvidia GPUs | 'gpu', or 'cudax.x-cudnnx.x' e.g., 'cuda10.0-cudnn7.3' |
| `devel` | indicator for development | if absent, SINGA Python package is installed for runtime only; if present, the building environment is also created, you can recompile SINGA from source at '/root/singa' |
+| `OS` | indicate OS version number | 'ubuntu16.04', 'ubuntu18.04' |
## From source
