strconv: make code formatting more consistent in doc.go

Replaces " \t" code indentation with "\t".

Issues like this are easy to spot with editor that prints
whitespace charecters.

Change-Id: Ia82877e7c99121bf369fa76e46ba52dff84f36bf
Reviewed-on: https://go-review.googlesource.com/101355Reviewed-by: Daniel Martí <mvdan@mvdan.cc>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/strconv/doc.go

@@ -32,10 +32,10 @@
 //
 // FormatBool, FormatFloat, FormatInt, and FormatUint convert values to strings:
 //
-// 	s := strconv.FormatBool(true)
-// 	s := strconv.FormatFloat(3.1415, 'E', -1, 64)
-// 	s := strconv.FormatInt(-42, 16)
-// 	s := strconv.FormatUint(42, 16)
+//	s := strconv.FormatBool(true)
+//	s := strconv.FormatFloat(3.1415, 'E', -1, 64)
+//	s := strconv.FormatInt(-42, 16)
+//	s := strconv.FormatUint(42, 16)
 //
 // AppendBool, AppendFloat, AppendInt, and AppendUint are similar but
 // append the formatted value to a destination slice.