add more help text

cmd/pell.go

@@ -60,10 +60,13 @@ func pell(cmd *cobra.Command, args []string) {
 
 // pellCmd represents the pell command
 var pellCmd = &cobra.Command{
-	Use:   "pell",
+	Use:   "pell -d N",
 	Short: "Find solutions to a Pell equation",
-	Long:  `Find solutions to a Pell equation x^2 - dy^2 = 1.`,
-	Run:   pell,
+	Long: `Find integer solutions to a Pell equation x^2 - dy^2 = 1.
+
+This will output solutions infinitely. Try piping to head to only output a certain number of solutions, like this:
+mathtools pell -d 12 | head -n 5`,
+	Run: pell,
 }
 
 func init() {