Add a crash course to debugging using about:net-internals.

net/net.gypi

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # This file is shared between the regular GYP build, the NaCl GYP build, and
 # the GN build. For GN support, it must have no conditionals or anything like
 # that beyond the simple one-level-deep dictionary of values.
 {
   'variables': {
     # Subset of net source files that are compiled for NaCl (net_nacl target).
@@ skipping 1908 matching lines @@
       "websockets/websocket_stream.cc",
       "websockets/websocket_stream.h",
     ],
     'net_docs_script': 'tools/net_docs/net_docs.py',
     'net_docs_sources': [
       'README.md',
       'docs/bug-triage.md',
       'docs/bug-triage-labels.md',
       'docs/bug-triage-suggested-workflow.md',
       'docs/code-patterns.md',
+      'docs/crash-course-in-net-internals.md',
       'docs/life-of-a-url-request.md',
       'sdch/README.md',
     ],
     'net_docs_output_dir': '<(PRODUCT_DIR)/net/docs',
   }
 }