update docs to include gcp estimation

Author: jordanstephens

docs/concepts/estimation.md

@@ -9,17 +9,17 @@ sidebar_position: 280
 Defang enables you to estimate the cost of deploying and running your project without needing to create an account with your cloud provider.
 
 :::info
-Currently, AWS is the only provider supported for cost estimation. Support for GCP and Digital Ocean is coming soon.
+Currently, AWS and GCP are supported for cost estimation. Support for Digital Ocean is coming soon.
 :::
 
 ## Generating an Estimate
 
 Navigate your shell to your application's working directory and run
 ```
-defang estimate [--provider aws] [--mode affordable|balanced|high_availability]
+defang estimate [--provider=aws|gcp] [--mode=affordable|balanced|high_availability]
 ```
 
-Here is an example of the output you would see if you estimated the cost deploying the [django-postgres](https://github.com/DefangLabs/samples/tree/main/samples/django-postgres) sample using the `balanced` [deployment mode](/docs/concepts/deployment-modes).
+Here is an example of the output you would see if you estimated the cost deploying the [django-postgres](https://github.com/DefangLabs/samples/tree/main/samples/django-postgres) to AWS sample using the `balanced` [deployment mode](/docs/concepts/deployment-modes).
 
 ```
 defang estimate --provider=aws --mode=balanced