net/http/pprof: adjust URL in package doc

The indentation makes the URL be treated as a code block,
thus preventing automatic detection of this URL.
Avoid using a code block for this.

Change-Id: Ie37ae18ec0969ef2d5a6e3b92b2512dac093dbf6
Reviewed-on: https://go-review.googlesource.com/c/go/+/478015
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Auto-Submit: Dmitri Shuralyov <dmitshur@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>

Author: dsnet

src/net/http/pprof/pprof.go

@@ -66,8 +66,7 @@
 // in your browser.
 //
 // For a study of the facility in action, visit
-//
-//	https://blog.golang.org/2011/06/profiling-go-programs.html
+// https://blog.golang.org/2011/06/profiling-go-programs.html.
 package pprof
 
 import (