Fix Documentation mentioning faulty Namespace for SOAP Webservices

This PR is for branch `2.0` @DavertMik see codeception/codeception#1241

It looks like i misunderstood «Bugfixes should be sent to to current stable branch, which is the same as major version number.» in [readme.md](/Codeception/Codeception/blob/2.0/readme.md) as beeing asked to commit to `1.8` which is marked as **stable**.