Add tool man pages in asciidoc format

tools/exception_port_tool.cc

 // Copyright 2014 The Crashpad Authors. All rights reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //     http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
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 "  -T, --show_new_task            display modified task exception ports\n"
 "      --show_new_thread          display modified thread exception ports\n"
 "  -n, --numeric                  display values numerically, not symbolically\n"
 "      --help                     display this help and exit\n"
 "      --version                  output version information and exit\n"
 "\n"
 "Any operations on host exception ports require superuser permissions.\n"
 "\n"
 "DESCRIPTION is formatted as a comma-separated sequence of tokens, where each\n"
 "token consists of a key and value separated by an equals sign. Available keys:\n"
-"  target    which target's exception ports to set: host, task, or target\n"
+"  target    which target's exception ports to set: host, task, or thread\n"
 "  mask      the mask of exception types to handle: CRASH, ALL, or others\n"
 "  behavior  the specific exception handler routine to call: DEFAULT, STATE,\n"
 "            or STATE_IDENTITY, possibly with MACH_EXCEPTION_CODES.\n"
 "  flavor    the thread state flavor passed to the handler: architecture-specific\n"
 "  handler   the exception handler: NULL or bootstrap:SERVICE, indicating that\n"
 "            the handler should be looked up with the bootstrap server\n"
 "The default DESCRIPTION is\n"
 "  target=task,mask=CRASH,behavior=DEFAULT|MACH,flavor=NONE,handler=NULL\n",
           me.c_str());
   ToolSupport::UsageTail(me);
@@ skipping 236 matching lines @@
 
   return kExitSuccess;
 }
 
 }  // namespace
 }  // namespace crashpad
 
 int main(int argc, char* argv[]) {
   return crashpad::ExceptionPortToolMain(argc, argv);
 }