docs: Add Clear Linux installation guide.

This commit documents the steps needed to setup Clear Containers
3.0 in Clear Linux.

Fixes clearcontainers#601.

Signed-off-by: Salvador Fuentes <salvador.fuentes@intel.com>

docs/clearlinux-installation-guide.md

@@ -0,0 +1,53 @@
+# Installing Clear Containers 3.0 on Clear Linux\*
+
+Clear Containers 3.0 is available in Clear Linux since version **17890**.
+
+Note:
+
+If you already have a previous Clear Linux version with Clear Containers 2.x installed,
+just update your OS to the latest version to get Clear Containers 3.0.
+
+1. Run the `swupd` command to ensure the host is using the latest version of Clear Linux.
+
+   ```
+   $ sudo swupd update
+   ```
+
+2. Install the Clear Containers bundle.
+
+   ```
+   $ sudo swupd bundle-add containers-virt
+   ```
+
+3. Start the Docker\* and Clear Containers `systemd` services.
+
+   ```
+   $ sudo systemctl enable docker
+   $ sudo systemctl start docker
+   $ sudo systemctl enable cc3-proxy
+   $ sudo systemctl start cc3-proxy
+   ```
+
+4. Run Clear Containers 3.0.
+
+   You are now ready to run Clear Containers 3.0. For example:
+
+   ```
+   $ sudo docker run -ti busybox sh
+   ```
+
+## More information about Docker in Clear Linux.
+
+Docker on Clear Linux provides a `docker.service` service file to start the `docker` daemon.
+The daemon will use `runc` or `cc-runtime` depending on the environment:
+
+If you are running Clear Linux on baremetal or on a VM with Nested Virtualization activated,
+`docker` will use `cc-runtime` as the default runtime. If you are running Clear Linux
+on a VM without Nested Virtualization, `docker` will use `runc` as the default runtime.
+It is not necessary to configure Docker to use `cc-runtime` manually since Docker itself
+will automatically use this runtime on systems that support it.
+
+To check which runtime your system is using, run:
+```
+$ sudo docker info | grep Runtime
+```