track1 add batch tag machine learning services in readme.go.md (#15432)

* track1 add batch tag machine learning services in readme.go.md

* fix

Author: Alancere

specification/machinelearningservices/resource-manager/readme.go.md

@@ -14,6 +14,7 @@ go:
 ```yaml $(go) && $(multiapi)
 batch:
   - tag: package-2021-07-01
+  - tag: package-2021-04-01
   - tag: package-2021-03-01-preview
   - tag: package-2020-04-01
   - tag: package-2020-03-01
@@ -25,6 +26,7 @@ batch:
   - tag: package-2020-02-18-preview
   - tag: package-2018-03-preview
 ```
+
 ## Tag: package-2021-07-01 and go
 
 These settings apply only when `--tag=package-2021-07-01 --go` is specified on the command line.
@@ -34,6 +36,15 @@ Please also specify `--go-sdk-folder=<path to the root directory of your azure-s
 output-folder: $(go-sdk-folder)/services/$(namespace)/mgmt/2021-07-01/$(namespace)
 ```
 
+## Tag: package-2021-04-01 and go
+
+These settings apply only when `--tag=package-2021-04-01 --go` is specified on the command line.
+Please also specify `--go-sdk-folder=<path to the root directory of your azure-sdk-for-go clone>`.
+
+```yaml $(tag)=='package-2021-04-01' && $(go)
+output-folder: $(go-sdk-folder)/services/$(namespace)/mgmt/2021-04-01/$(namespace)
+```
+
 ## Tag: package-2021-03-01-preview and go
 
 These settings apply only when `--tag=package-2021-03-01-preview --go` is specified on the command line.