message: add gosdk version in readme.go.md
diff: @@ -13,6 +13,7 @@ go:
  ``` yaml $(go) && $(multiapi)
  batch:
  + - tag: package-2021-05
  - tag: package-2021-04
  - tag: package-2021-04-preview
  - tag: package-2021-03
  @@ -28,6 +29,15 @@ batch:
  - tag: package-2015-04
  ```
  +### Tag: package-2021-05 and go
  +
  +These settings apply only when `--tag=package-2021-05 --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-2021-05' && $(go)
  +output-folder: $(go-sdk-folder)/services/cosmos-db/mgmt/2021-05-15/$(namespace)
  +```
  +
  ### Tag: package-2021-04 and go
  These settings apply only when `--tag=package-2021-04 --go` is specified on the command line.
  