fix: make expected results more descriptive for numbers exercises

08-numbers-and-strings/01-numbers/exercises/08-sphere-area/main.go

@@ -28,7 +28,11 @@ import (
 //  https://golang.org/pkg/math/#Pow
 //
 // EXPECTED OUTPUT
+//  go run main.go 10
 //    1256.64
+//
+//  go run main.go 54.2
+//    36915.47
 // ---------------------------------------------------------
 
 func main() {

08-numbers-and-strings/01-numbers/exercises/09-sphere-volume/main.go

@@ -25,7 +25,11 @@ import (
 //  Use `math.Pow` to calculate the volume
 //
 // EXPECTED OUTPUT
+//  go run main.go 10
 //    4188.79
+//
+//  go run main.go .5
+//    0.52
 // ---------------------------------------------------------
 
 func main() {