Rename cookie example

At https://gerrit.openbmc.org/c/openbmc/bmcweb/+/77539 we are going to
rename the BMCWEB session cookie to be BMCWEB-SESSION.

I don't see actual code in openbmc-test-automation that relies on this
but might as well update the documentation.

Change-Id: I928d25ee2d76ac55b6e61b27cdc6577a2ced3b98
Signed-off-by: Gunnar Mills <gmills@us.ibm.com>
diff --git a/lib/rest_client.robot b/lib/rest_client.robot
index 4e35354..6a8e731 100644
--- a/lib/rest_client.robot
+++ b/lib/rest_client.robot
@@ -175,7 +175,7 @@
 
     # Example result data:
     # 'XSRF-TOKEN=hQuOyDJFEIbrN4aOg2CT; Secure,
-    # SESSION=c4wloTiETumSxPI9nLeg; Secure; HttpOnly'
+    # BMCWEB-SESSION=c4wloTiETumSxPI9nLeg; Secure; HttpOnly'
     Set Global Variable  ${XAUTH_TOKEN}  ${result['session']}