strconv: add missing package name into doc.go(godoc overview)

Change-Id: I336ad707a85bf0c81b6c2230c90452c0b3b92924
Reviewed-on: https://go-review.googlesource.com/c/155998Reviewed-by: Robert Griesemer <gri@golang.org>

src/strconv/doc.go

@@ -46,8 +46,8 @@
 // The latter guarantees that the result is an ASCII string, by escaping
 // any non-ASCII Unicode with \u:
 //
-//	q := Quote("Hello, 世界")
-//	q := QuoteToASCII("Hello, 世界")
+//	q := strconv.Quote("Hello, 世界")
+//	q := strconv.QuoteToASCII("Hello, 世界")
 //
 // QuoteRune and QuoteRuneToASCII are similar but accept runes and
 // return quoted Go rune literals.