message: add tag in python.md
diff: @@ -35,6 +35,7 @@ Generate all API versions currently shipped for this package
  ```yaml $(multiapi)
  clear-output-folder: true
  batch:
  + - tag: package-2021-03-01
  - tag: package-2020-12-01-only
  - tag: package-2020-10-01-preview-only
  - tag: package-2020-09-30-only
  @@ -65,6 +66,16 @@ clear-output-folder: false
  perform-load: false
  ```
  +### Tag: package-2021-03-01
  +
  +These settings apply only when `--tag=package-2021-03-01 --python` is specified on the command line.
  +Please also specify `--python-sdks-folder=<path to the root directory of your azure-sdk-for-python clone>`.
  +
  +``` yaml $(tag) == 'package-2021-03-01'
  +namespace: azure.mgmt.compute.v2021_03_01
  +output-folder: $(python-sdks-folder)/compute/azure-mgmt-compute/azure/mgmt/compute/v2021_03_01
  +```
  +
  ### Tag: package-2020-12-01-only and python
  These settings apply only when `--tag=package-2020-12-01-only --python` is specified on the command line.
  