Document GitHub Action installation

INSTALL.md

@@ -99,6 +99,10 @@ We currently publish these Docker tags:
 
 You can find all source Dockerfiles in the `/docker` folder ([here](https://github.com/DopplerHQ/cli/tree/master/docker)).
 
+## GitHub Action
+
+You can install the latest version of the CLI via GitHub Action. See the cli-action [repo](https://github.com/DopplerHQ/cli-action) for more info.
+
 ### Example
 Here's an example Dockerfile for a Node app:
 

README.md

@@ -10,7 +10,7 @@ The Doppler CLI is the official tool for interacting with your Enclave secrets a
 
 ## Install
 
-The Doppler CLI is available in several popular package managers. It can also be installed via [shell script](https://github.com/DopplerHQ/cli/blob/master/INSTALL.md#shell-script), and downloaded as a [standalone binary](https://github.com/DopplerHQ/cli/releases/latest).
+The Doppler CLI is available in several popular package managers. It can also be installed via [shell script](https://github.com/DopplerHQ/cli/blob/master/INSTALL.md#shell-script), [GitHub Action](https://github.com/DopplerHQ/cli-action), or downloaded as a [standalone binary](https://github.com/DopplerHQ/cli/releases/latest).
 
 For more info, including instructions on verifying binary signatures, see the [Install](INSTALL.md) page.
 
@@ -70,6 +70,10 @@ We currently build these Docker images:
 
 For more info, see the [Install](INSTALL.md#docker) page.
 
+### GitHub Action
+
+You can install the latest version of the CLI via GitHub Action. See the cli-action [repo](https://github.com/DopplerHQ/cli-action) for more info.
+
 ## Usage
 
 Once installed, setup should only take a minute. You'll authorize the CLI to access your Doppler workplace, and then select your project and config.