fix: close EnterpriseKnowledgeGraph go fence (Azure#6547)

* fix: close EnterpriseKnowledgeGraph go fench

* fix Go SDK build

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

@@ -5,29 +5,20 @@ These settings apply only when `--go` is specified on the command line.
 ``` yaml $(go)
 go:
   license-header: MICROSOFT_APACHE_NO_VERSION
-  namespace: EnterpriseKnowledgeGraphService
+  namespace: enterpriseknowledgegraphservice
   clear-output-folder: true
 ```
 
 ### Go multi-api
 ``` yaml $(go) && $(multiapi)
 batch:
    - tag: package-2018-12-03
-   - tag: package-2018-12-03-preview
 ```
 
-### Tag: package-2018-12 and go
-These settings apply only when `--tag=package-2018-12 --go` is specified on the command line.
+### Tag: package-2018-12-03 and go
+These settings apply only when `--tag=package-2018-12-03 --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-2018-12' && $(go)
-output-folder: $(go-sdk-folder)/services/$(namespace)/2018-12-03/$(namespace)
+``` yaml $(tag) == 'package-2018-12-03' && $(go)
+output-folder: $(go-sdk-folder)/services/preview/$(namespace)/2018-12-03/$(namespace)
 ```
-
-### Tag: package-2018-12-preview and go
-These settings apply only when `--tag=package-2018-12-preview --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-2018-12-preview' && $(go)
-output-folder: $(go-sdk-folder)/services/preview/$(namespace)/2018-12-31-preview/$(namespace)
-