_content/play.tmpl: remove unnecessary spaces

Change-Id: I616f2afe682215e7a0cf353dafd7aa930bffd1fb
GitHub-Last-Rev: 42fd1858b0
GitHub-Pull-Request: golang/website#180
Reviewed-on: https://go-review.googlesource.com/c/website/+/425814
Reviewed-by: Robert Findley <rfindley@google.com>
Reviewed-by: Yasuhiro Matsumoto <mattn.jp@gmail.com>
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
Reviewed-by: Hajime Hoshi <hajimehoshi@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Jamal Carvalho <jamal@golang.org>
Run-TryBot: Hyang-Ah Hana Kim <hyangah@gmail.com>
Auto-Submit: Hyang-Ah Hana Kim <hyangah@gmail.com>

_content/play.tmpl

@@ -51,8 +51,7 @@ import "fmt"
 
 func main() {
 	fmt.Println("Hello, 世界")
-}
-{{end}}      </textarea>
+}{{end}}</textarea>
     </div>
   </div>
   <div class="Playground-outputContainer js-playgroundOutputEl">