[Compute] Update readme.python.md (#11003)

* add 2020-09-30 to python readme

* Make HyperVGen modelAsString in sharedGallery.json

Co-authored-by: Grace Liang <grlian@microsoft.com>

specification/compute/resource-manager/Microsoft.Compute/preview/2020-09-30/sharedGallery.json

@@ -532,7 +532,7 @@
           ],
           "x-ms-enum": {
             "name": "HyperVGeneration",
-            "modelAsString": false
+            "modelAsString": true
           }
         },
         "features": {

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

@@ -44,6 +44,7 @@ Generate all API versions currently shipped for this package
 
 ```yaml $(multiapi) && !$(track2)
 batch:
+  - tag: package-2020-09-30-only
   - tag: package-2020-06-30-only
   - tag: package-2020-06-01-only
   - tag: package-2020-05-01-only
@@ -67,6 +68,7 @@ batch:
 ```yaml $(multiapi) && $(track2)
 clear-output-folder: true
 batch:
+  - tag: package-2020-09-30-only
   - tag: package-2020-06-30-only
   - tag: package-2020-06-01-only
   - tag: package-2020-05-01-only
@@ -94,6 +96,19 @@ clear-output-folder: false
 perform-load: false
 ```
 
+### Tag: package-2020-09-30-only and python
+
+These settings apply only when `--tag=package-2020-09-30-only --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-2020-09-30-only'
+namespace: azure.mgmt.compute.v2020_09_30
+output-folder: $(python-sdks-folder)/compute/azure-mgmt-compute/azure/mgmt/compute/v2020_09_30
+python:
+  namespace: azure.mgmt.compute.v2020_09_30
+  output-folder: $(python-sdks-folder)/compute/azure-mgmt-compute/azure/mgmt/compute/v2020_09_30
+```
+
 ### Tag: package-2020-06-30-only and python
 
 These settings apply only when `--tag=package-2020-06-30-only --python` is specified on the command line.