Documentation not updated to add the possibility of setting cookie secure

Issue in ./help/introduction.md

The documentation says that we cannot set the s_cc and mbox cookies as secure but that is old information as now the configurations are available. For example, for mbox there is a way described in below article:

https://developer.adobe.com/target/implement/client-side/atjs/atjs-functions/targetglobalsettings/?lang=en

Open help/introduction.md and compare its statement about securing the s_cc and mbox cookies with the linked Adobe Target configuration article. Update the outdated documentation to reflect that secure-cookie configuration is available, then verify the file no longer says these cookies cannot be set as secure.

Written by the indexing model from the issue text.