_content/blog: fix example code in range-functions post

Lines returns a iter.Seq, not iter.Seq2,
so there's only one value to range over.

Change-Id: I37ea040c73b469978a2e1a78f6436775a7b63d80
Reviewed-on: https://go-review.googlesource.com/c/website/+/611655
Auto-Submit: Dmitri Shuralyov <[email protected]>
Reviewed-by: Dmitri Shuralyov <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>

_content/blog/range-functions.md

@@ -740,7 +740,7 @@ func Lines(data []byte) iter.Seq[[]byte] {
 Now our code to loop over the lines of a byte slice looks like this.
 
 ```
-	for _, line := range Lines(data) {
+	for line := range Lines(data) {
 		handleLine(line)
 	}
 ```