Add user manual

Author: gustavosbarreto

docs/user-manual/index.md

@@ -0,0 +1,2 @@
+This manual covers usage of the ShellHub Agent and ShellHub UI.
+

docs/user-manual/installing.md

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+ShellHub Agent is designed to run on all your systems: physical and virtual servers, even IoT/edge devices.
+
+The best way to install ShellHub Agent is with our automatic one-line installation script, which works with all Linux distributions that have Docker installed and properly set up.
+
+If you want to install ShellHub without Docker you can try to build by yourself or if you are targeting embedded devices checkout our [Yocto Project support layer for ShellHub](https://github.com/shellhub-io/meta-shellhub).
+
+## One-line installation script
+
+!!! info "Docker installed and properly set up on device is required"
+	Follow the [Docker Install Instructions](http://docs.docker.com/installation/) for your distro/platform.
+	You should always use the latest docker version. The minimum supported Docker version is `18.06`.
+
+Open the ShellHub UI, navigate to _Devices_ on the sidebar, and click on _ADD DEVICE_. It should give you a registration command for installing ShellHub Agent that you need to run on your device:
+
+![Device Register](/img/register-device.png)
+
+After running the command on your device, you'll need to accept the device on the ShellHub UI in order to complete enrollment.
+Go to _Devices_ -> _Pending_ locate your device and click _Accept_ button.
+
+After your device is enrolled, it becomes available in _Device List_ page.

mkdocs.yml

@@ -98,6 +98,9 @@ nav:
       - Running: admin-manual/running.md
       - Managing: admin-manual/managing.md
       - Production Deployment: admin-manual/production-deployment.md
+  - User Manual:
+      - Introduction: user-manual/index.md
+      - Installing: user-manual/installing.md
   - Troubleshooting:
       Frequently Encountered Issues: troubleshooting.md
 # Extra data