doc: Adds support for SDK_BRANCH in schema generation (#2562)

* doc: Add support for SDK_BRANCH

* chore: revert unintentional change on save

* doc: remove, can be confusing to users without cloud-dev access

scripts/schema-scaffold.sh

@@ -3,8 +3,9 @@ set -euo pipefail
 
 : "${1?"Name of resource or data source must be provided."}"
 
+SDK_BRANCH="${SDK_BRANCH:-"main"}"
 # URL to download Atlas Admin API Spec
-atlas_admin_api_spec="https://raw.githubusercontent.com/mongodb/atlas-sdk-go/main/openapi/atlas-api-transformed.yaml"
+atlas_admin_api_spec="https://raw.githubusercontent.com/mongodb/atlas-sdk-go/${SDK_BRANCH}/openapi/atlas-api-transformed.yaml"
 
 echo "Downloading api spec"
 curl -L "$atlas_admin_api_spec" -o "./api-spec.yml"