[Edgeorder] Update readme.python.md (Azure#22566)

* Update readme.python.md

* Update readme.python.md

---------

Co-authored-by: Yuchao Yan <yuchaoyan@microsoft.com>

Author: 2 people

specification/edgeorder/resource-manager/readme.python.md

@@ -22,6 +22,7 @@ Generate all API versions currently shipped for this package
 
 ```yaml $(python)
 multiapi: true
+default-api-version: "2021-12-01"
 batch:
   - tag: package-2022-05-preview
   - tag: package-2021-12
@@ -62,4 +63,4 @@ Please also specify `--python-sdks-folder=<path to the root directory of your az
 ``` yaml $(tag) == 'package-2020-12-preview' && $(python)
 namespace: azure.mgmt.edgeorder.v2020_12_01_preview
 output-folder: $(python-sdks-folder)/edgeorder/azure-mgmt-edgeorder/azure/mgmt/edgeorder/v2020_12_01_preview
-```
+```