Add section on how to get Corso (#1270)

## Description

Add instructions on where to get Corso binaries

## Type of change

- [x] 🗺️ Documentation

docs/docs/quickstart.md

@@ -45,7 +45,8 @@ Obtaining credentials from Microsoft 365 to allow Corso to run is a one-time ope
 
 ## Repository creation
 
-To create a secure backup location for Corso, you will need to initialize the Corso repository using an
+To create a secure backup location for Corso, you will first need to [download Corso](setup/download).
+Use the container or native executable to initialize the Corso repository using an
 [encryption passphrase](/setup/configuration#environment-variables) and a pre-created S3 bucket (Corso doesn't create
 the bucket if it doesn't exist). The steps below use `corso-test` as the bucket name but, if you are using AWS, you
 will need a different unique name for the bucket.
@@ -264,7 +265,7 @@ A confirmation of the recovered email will be shown and the email will appear in
   360bf6840396  phish@contoso.info     Re: Request for Apple/Amazon gift cards  2022-10-18T02:27:47Z
 ```
 
-## Next Steps
+## Next steps
 
 The above tutorial only scratches the surface for Corso's capabilities. We encourage you to dig deeper by:
 

docs/docs/setup/download.md

@@ -0,0 +1,19 @@
+# Downloads
+
+Corso is available as a Docker container image or as native binaries.
+
+## Docker container images
+
+The Corso Docker container image is available for Linux (`x86_64` and `arm64`) and this can be used on Linux, with
+Docker Desktop on macOS, and on Windows in
+[Linux Mode](https://docs.microsoft.com/en-us/virtualization/windowscontainers/quick-start/quick-start-windows-10-linux).
+These Docker containers can be pulled from [GitHub's container registry](https://github.com/alcionai/corso/pkgs/container/corso).
+
+We strongly recommend using a container image with the release version tag (for example,
+`ghcr.io/alcionai/corso:v0.1.0`) but container images with the `latest` tag are also available. Unreleased builds
+with the `nightly` tag are also provided for testing but these are likely to be unstable.
+
+## Native binaries
+
+Corso is also available as an `x86_64` and `arm64` executable for Windows, Linux and macOS. These can be downloaded from
+the [GitHub releases page](https://github.com/alcionai/corso/releases).

docs/sidebars.js

@@ -20,7 +20,7 @@ const sidebars = {
     {
       type: 'category',
       label: 'Corso setup',
-      items: ['setup/concepts', 'setup/m365_access', 'setup/configuration', 'setup/repos'],
+      items: ['setup/concepts', 'setup/download', 'setup/m365_access', 'setup/configuration', 'setup/repos'],
     },
     {
       type: 'category',