Add a Tooltip/Description attribute to Envelope Custom Fields

Would love to be able to have an explaining definition/tooltip for the Envelope Custom Fields just like we do for fields on the document.  Example uses

Custom Field: “Accounts” 

Tooltip: “Include leading zeroes.  Separate account numbers by semi-colon.”

Custom Field: “Priority Code”

Tooltip: “G - General, R - Rush, A - Archive”