Fix GN docs for 'gn help deps' and update reference.md.

tools/gn/variables.cc

 // Copyright (c) 2013 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.
 
 #include "tools/gn/variables.h"
 
 namespace variables {
 
 // Built-in variables ----------------------------------------------------------
 
@@ skipping 665 matching lines @@
 
 const char kDeps[] = "deps";
 const char kDeps_HelpShort[] =
     "deps: [label list] Private linked dependencies.";
 const char kDeps_Help[] =
     "deps: Private linked dependencies.\n"
     "\n"
     "  A list of target labels.\n"
     "\n"
     "  Specifies private dependencies of a target. Shared and dynamic\n"
-    "  libraries will be linked into the current target. Other target types\n"
-    "  that can't be linked (like actions and groups) listed in \"deps\" will\n"
-    "  be treated as \"data_deps\". Likewise, if the current target isn't\n"
-    "  linkable, then all deps will be treated as \"data_deps\".\n"
+    "  libraries will be linked into the current target.\n"
     "\n"
     "  These dependencies are private in that it does not grant dependent\n"
     "  targets the ability to include headers from the dependency, and direct\n"
     "  dependent configs are not forwarded.\n"
     "\n"
     "  See also \"public_deps\" and \"data_deps\".\n";
 
 // TODO(brettw) remove this, deprecated.
 const char kForwardDependentConfigsFrom[] = "forward_dependent_configs_from";
 const char kForwardDependentConfigsFrom_HelpShort[] =
@@ skipping 572 matching lines @@
     INSERT_VARIABLE(Sources)
     INSERT_VARIABLE(Testonly)
     INSERT_VARIABLE(Visibility)
   }
   return info_map;
 }
 
 #undef INSERT_VARIABLE
 
 }  // namespace variables