Add upgrade docs

Author: ospillinger

docs/cluster/install.md

@@ -24,7 +24,7 @@ export AWS_SECRET_ACCESS_KEY=***
 ./cortex.sh install
 ```
 
-See [cluster configuration](config.md) options to customize your installation.
+See [cluster configuration](config.md) to customize your installation.
 
 ## Installing and configuring the CLI
 

docs/cluster/upgrade.md

@@ -0,0 +1,33 @@
+# Upgrade
+
+## Prerequisites
+
+1. [AWS credentials](aws.md)
+2. [Docker](https://docs.docker.com/install)
+
+## Upgrading Cortex
+
+See [cluster configuration](config.md) to customize your installation.
+
+<!-- CORTEX_VERSION_MINOR -->
+
+```bash
+# Download
+curl -O https://github.com/raw/cortexlabs/cortex/master/cortex.sh
+
+# Change permissions
+chmod +x cortex.sh
+
+# Set AWS credentials
+export AWS_ACCESS_KEY_ID=***
+export AWS_SECRET_ACCESS_KEY=***
+
+# Upgrade Cortex
+./cortex.sh upgrade
+
+# Upgrade the CLI
+./cortex.sh install cli
+
+# Confirm version
+cortex --version
+```

docs/summary.md

@@ -22,6 +22,7 @@
 * [AWS Credentials](cluster/aws.md)
 * [Configuration](cluster/config.md)
 * [Security](cluster/security.md)
+* [Upgrade](cluster/upgrade.md)
 * [Uninstall](cluster/uninstall.md)
 * [Development](cluster/development.md)