doc: Effective Go: formatting of code example

Change-Id: I7f5947cef3ec43746f60abca556dda29a705caf7
GitHub-Last-Rev: b9aefd06abdaee854671451711579dd5bd33bd26
GitHub-Pull-Request: golang/go#35404
Reviewed-on: https://go-review.googlesource.com/c/go/+/205610Reviewed-by: Rob Pike <r@golang.org>

doc/progs/eff_qr.go

@@ -41,9 +41,9 @@ const templateStr = `
 <br>
 <br>
 {{end}}
-<form action="/" name=f method="GET"><input maxLength=1024 size=70
-name=s value="" title="Text to QR Encode"><input type=submit
-value="Show QR" name=qr>
+<form action="/" name=f method="GET">
+	<input maxLength=1024 size=70 name=s value="" title="Text to QR Encode">
+	<input type=submit value="Show QR" name=qr>
 </form>
 </body>
 </html>