Add steps to delete tutorial assets to the conclusion page

Non-Platform customers cannot do the tutorial in a development sandbox and then delete the sandbox once they're done. These customers need to build the tutorial assets in their Prod sandbox and should be instructed to clean it up when they are done.

Locate the tutorial's conclusion page in the documentation and review the existing cleanup guidance. Add steps explaining how Non-Platform customers should delete the tutorial assets from their Prod sandbox, then verify the rendered conclusion page clearly covers cleanup.

Written by the indexing model from the issue text.