add Unique cookie name article

Signed-off-by: Andrew Jandacek <[email protected]>

docs/user-guide/unique-cookie-name-for-multiple-zowe-instances.md

@@ -0,0 +1,14 @@
+# Unique cookie name for multiple zowe instances
+
+By default, in the API Gateway, the cookie name is `apimlAuthenticationToken`.
+To prevent overwriting of the default cookie name in the case of multiple Zowe instances, a unique cookie name can be configured for each instance.  
+
+Follow this procedure to configure a unique cookie name for the instances:
+
+1. Open the `zowe.yaml` configuration file.
+2. Find or add the property  `components.gateway.apiml.security.auth.uniqueCookie`, and set it to `true`. A unique cookie name is generated as `apimlAuthenticationToken.cookieIdentifier`.
+
+    **Example:**  
+    If this parameter is set to `true`, and the cookieIdentifier is `1`, the name of the cookie transforms to `apimlAuthenticationToken.1`.  
+    If this property is not set to `true`, the cookie name remains `apimlAuthenticationToken` by default.
+3. Restart Zowe.