update digitalocean docs on droplets (#14659)

Make note of smaller/cheaper droplets for DigitalOcean and document it.

config.cfg

@@ -176,6 +176,8 @@ cloud_providers:
       sku: minimal-22_04-daily-lts
       version: latest
   digitalocean:
+    # See docs for extended droplet options, pricing, and availability.
+    # Possible values: 's-1vcpu-512mb-10gb', 's-1vcpu-1gb', ...
     size: s-1vcpu-1gb
     image: "ubuntu-22-04-x64"
   ec2:

docs/cloud-do.md

@@ -18,6 +18,18 @@ You will be returned to the **Tokens/Keys** tab, and your new key will be shown
 
 Copy or note down the hash that shows below the name you entered, as this will be necessary for the steps below. This value will disappear if you leave this page, and you'll need to regenerate it if you forget it.
 
+## Select a Droplet (optional)
+
+The default option is the `s-1vcpu-1gb` because it is available in all regions. However, you may want to switch to a cheaper droplet such as `s-1vcpu-512mb-10gb` even though it is not available in all regions. This can be edited in the [Configuration File](config.cfg) under `cloud_providers > digitalocean > size`. See this brief comparison between the two droplets below:
+
+| Droplet Type | Monthly Cost | Bandwidth | Availability |
+|:--|:-:|:-:|:--|
+| `s-1vcpu-512mb-10gb` | $4/month | 0.5 TB | Limited |
+| `s-1vcpu-1gb`        | $6/month | 1.0 TB | All regions |
+| ... | ... | ... | ... |
+
+*Note: Exceeding bandwidth limits costs $0.01/GiB at time of writing ([docs](https://docs.digitalocean.com/products/billing/bandwidth/#droplets)). See the live list of droplets [here](https://slugs.do-api.dev/).*
+
 ## Using DigitalOcean with Algo (interactive)
 
 These steps are for those who run Algo using Docker or using the `./algo` command.