change arg description to comment as per LS

[Vasileios-Mavroeidis]

No description provided.

[dlemire60]

Seeking to clarify: I believe the intent here is that command arguments, as described in Table 2.1.3-1 of the PF AP, don't include the comment field, as defined in LS 3.3.1.4, and that field needs to be added.