When publishing an assessment, the first two items you will see are the Reason for Publishing and Commentstext boxes. See the screenshot below:

These are optional and do not need to be filled in. They are there just in case you wish to add any notes before publishing your assessment. For example, lets say you've just publish an assessment, and then notice that you have made a spelling mistake. Naturally, you would reload the assessment wizard and amend the incorrect spelling. Once amended, you would then go to step 9 of the assessment wizard and republish it to update the published document. In months to come, it may be handy if you have added notes to remind yourself, or to inform others of why the assessment was republished so soon after the original.