_content/blog/range-functions: trim tailing newline in bytes.Split example

Otherwise we get a trailing blank line, which is not what we want.

Pointed out by dmitshur in CL 611655.

Change-Id: I6c2c0cbc6e19c06d392ce6e6fd108163020bd124
Reviewed-on: https://go-review.googlesource.com/c/website/+/610565
Commit-Queue: Ian Lance Taylor <iant@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@google.com>
Reviewed-by: Dmitri Shuralyov <dmitshur@golang.org>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>

_content/blog/range-functions.md

@@ -706,7 +706,9 @@ the lines in a byte slice.
 This is easy to write and fairly efficient.
 
 ```
-	for _, line := range bytes.Split(data, []byte{'\n'}) {
+	nl := []byte{'\n'}
+	// Trim a trailing newline to avoid a final empty blank line.
+	for _, line := range bytes.Split(bytes.TrimSuffix(data, nl), nl) {
 		handleLine(line)
 	}
 ```