Add info about if there is no slug to this instruction page

Why is this change being made?

@rvzon can you kindly review that my instruction makes logical sense? I noticed a few folks are not editing an exisiting post, as there isn't one and then the slug part is left out, therefore added this.

Does this MR meet the acceptance criteria?

Conformity

• Added description to this MR explaining the reasons for the proposed change, per say-why-not-just-what