sagews/jupyter: fix default mode example
sagews/jupyter: fix default mode example

tscholl2/smc,sagemathinc/smc,DrXyzzy/smc,tscholl2/smc,DrXyzzy/smc,tscholl2/smc,DrXyzzy/smc,DrXyzzy/smc,tscholl2/smc,sagemathinc/smc,sagemathinc/smc,sagemathinc/smc,tscholl2/smc