add doc comment

cmd/themis-server/main.go

@@ -486,6 +486,11 @@ func main() {
 					Components: []discordgo.MessageComponent{
 						discordgo.ActionsRow{
 							Components: []discordgo.MessageComponent{
+								// Note: Currently, Discord *requires* modal have at least one field present, it's not
+								// possible to simply have a cancel/confirm box. That is why this modal uses an old
+								// school [y/N] confirmation.
+								//
+								// source: https://stackoverflow.com/questions/71874810/discord-modals-without-textinputcomponent-but-a-text-and-button-only#answer-74317739
 								discordgo.TextInput{
 									CustomID:    "confirmation",
 									Label:       "Delete all claims permanently? [y/N]",