strconv: make docs for Itoa and Atoi slightly higher level

Fixes #29461

Change-Id: I5db8bc80e5bd0778dced8471581c67e66853aada
Reviewed-on: https://go-review.googlesource.com/c/155924
Reviewed-by: Rob Pike <r@golang.org>

src/strconv/atoi.go

@@ -198,7 +198,7 @@ func ParseInt(s string, base int, bitSize int) (i int64, err error) {
 	return n, nil
 }
 
-// Atoi returns the result of ParseInt(s, 10, 0) converted to type int.
+// Atoi is equivalent to ParseInt(s, 10, 0), converted to type int.
 func Atoi(s string) (int, error) {
 	const fnAtoi = "Atoi"
 

src/strconv/itoa.go

@@ -30,7 +30,7 @@ func FormatInt(i int64, base int) string {
 	return s
 }
 
-// Itoa is shorthand for FormatInt(int64(i), 10).
+// Itoa is equivalent to FormatInt(int64(i), 10).
 func Itoa(i int) string {
 	return FormatInt(int64(i), 10)
 }