add api-version of network for go SDK (#11890)

Author: ArcturusZhang

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

@@ -13,6 +13,7 @@ go:
 
 ``` yaml $(go) && $(multiapi)
 batch:
+  - tag: package-2020-07
   - tag: package-2020-06
   - tag: package-2020-05
   - tag: package-2020-04
@@ -48,6 +49,15 @@ batch:
   - tag: package-2015-05-preview
 ```
 
+### Tag: package-2020-07 and go
+
+These settings apply only when `--tag=package-2020-07 --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-2020-07' && $(go)
+output-folder: $(go-sdk-folder)/services/$(namespace)/mgmt/2020-07-01/$(namespace)
+```
+
 ### Tag: package-2020-06 and go
 
 These settings apply only when `--tag=package-2020-06 --go` is specified on the command line.