fix: make cli respect deployment --docs-url (#14568)

cli/testdata/coder_server_--help.golden

@@ -175,7 +175,7 @@ NETWORKING OPTIONS:
       --access-url url, $CODER_ACCESS_URL
           The URL that users will use to access the Coder deployment.
 
-      --docs-url url, $CODER_DOCS_URL
+      --docs-url url, $CODER_DOCS_URL (default: https://coder.com/docs)
           Specifies the custom docs URL.
 
       --proxy-trusted-headers string-array, $CODER_PROXY_TRUSTED_HEADERS

cli/testdata/server-config.yaml.golden

@@ -7,8 +7,8 @@ networking:
   # (default: <unset>, type: string)
   wildcardAccessURL: ""
   # Specifies the custom docs URL.
-  # (default: <unset>, type: url)
-  docsURL:
+  # (default: https://coder.com/docs, type: url)
+  docsURL: https://coder.com/docs
   # Specifies whether to redirect requests that do not match the access URL host.
   # (default: <unset>, type: bool)
   redirectToAccessURL: false