add sql tag to readme.go.md (Azure#14841)

Author: chenjianfei2017

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

@@ -15,6 +15,7 @@ From api-version 2017-10 and onwards, only pure package versions should be used.
 
 ``` yaml $(go) && $(multiapi)
 batch:
+  - tag: package-composite-v5
   - tag: package-composite-v4
   - tag: package-composite-v3
   - tag: package-pure-2018-06-preview
@@ -24,6 +25,15 @@ batch:
   - tag: package-pure-2014-04
 ```
 
+#### Tag: package-composite-v5 and go
+
+These settings apply only when `--tag=package-composite-v5 --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-composite-v5' && $(go)
+output-folder: $(go-sdk-folder)/services/preview/$(namespace)/mgmt/v5.0/$(namespace)
+```
+
 #### Tag: package-composite-v4 and go
 
 These settings apply only when `--tag=package-composite-v4 --go` is specified on the command line.