Expand working group and repo to all diagnostics.

Add additional top level to repo with subfolders for diagnostic domains.
Add initial README.md for each domain.
Add some initial docs and samples for domains beyond tracing.
Move and minor cleanup of AsyncWrap docs and background info on
TRACE_EVENT.

Author: joshgav

README.md

@@ -1,9 +1,24 @@
-# tracing-wg
+# Diagnostics Working Group  
+The goal of this WG is to ensure Node provides a set of comprehensive, documented, extensible diagnostic protocols, formats, and APIs to enable tool vendors to provide reliable diagnostic tools for Node.
 
-Tracing Working Group
+Work is divided into several domains:
+- [Tracing](./tracing)
+- [Profiling](./profiling)
+- [Heap and Memory Analysis](./heap-memory)
+- [Step Debugging](./debugging)
 
-# Members
+Background, reference documentation, samples, and discussion for each domain is contained within its folder.
 
+Work needed includes:  
+- Collect, understand, and document existing diagnostic capabilities and entry-points throughout Node, V8, and other components.
+- Collect and document projects and products providing diagnostics for Node with brief description of their technical architecture and sponsoring organizations.
+- Identify opportunities and gaps, then propose and implement solutions.
+
+### Logistics
+- Monthly Meetings
+- Biannual F2F
+
+### Members  
 * @bnoordhuis 
 * @sam-github 
 * @othiym23 
@@ -28,3 +43,5 @@ Tracing Working Group
 * @matthewloring
 * @pmuellr
 * @jeffolfert
+* @joshgav
+

debugging/README.md

@@ -0,0 +1,29 @@
+## Debugging API
+- [Chrome Debugging Protocol](https://chromedevtools.github.io/debugger-protocol-viewer/)
+- [V8 Debugging Protocol](https://github.com/v8/v8/wiki/Debugging-Protocol)
+
+Node currently relies on V8's internal Debug API and associated commands and events. The Debug API is published at [v8/include/v8-debug.h](https://github.com/v8/v8/blob/master/include/v8-debug.h), and the message protocol is documented in prose in [the V8 wiki](https://github.com/v8/v8/wiki/Debugging-Protocol) and in code in [v8/src/debug/debug.js#L2341-2372](https://github.com/v8/v8/blob/master/src/debug/debug.js#L2341-L2372). 
+
+Node also provides an agent [node/src/debug-agent.h](https://github.com/blob/master/src/debug-agent.h) which relays requests, responses, and events through a TCP socket, and a command-line debugger [node/lib/_debugger.js](https://github.com/blob/master/lib/_debugger.js).
+
+The Chrome/V8 team has deprecated the internal V8 API and command set and proposed replacing it with a subset of the Chrome Debugging Protocol (CrDP), see https://github.com/nodejs/node/issues/2546. CrDP is documented at [https://chromedevtools.github.io/debugger-protocol-viewer/]() and the backing GitHub repo.
+
+The [cyrus-and/chrome-remote-interface](https://github.com/cyrus-and/chrome-remote-interface) library provides a JS proxy for CrDP.
+
+## Step Debugging Tools  
+Name | Sponsor
+-----|--------
+[node-inspector][] | StrongLoop
+[JetBrains WebStorm][] | JetBrains
+[Visual Studio Code][] | Microsoft
+[Node CLI Debugger][] | Node Foundation
+[Chrome DevTools][] | Google
+[Theseus][] | Adobe Research
+
+[node-inspector]: https://github.com/node-inspector/node-inspector 
+[JetBrains WebStorm]: https://www.jetbrains.com/help/webstorm/2016.1/running-and-debugging-node-js.html
+[Visual Studio Code]: https://github.com/Microsoft/vscode
+[Node CLI Debugger]: https://nodejs.org/api/debugger.html
+[Chrome DevTools]: https://github.com/ChromeDevTools/devtools-frontend
+[Theseus]: https://github.com/adobe-research/theseus
+

docs/README.md

@@ -0,0 +1,10 @@
+## Heap and Memory Analysis  
+The [nodejs/post-mortem](https://github.com/nodejs/post-mortem) WG is responsible for this domain.
+
+### Heap Analysis  
+- [mdb_v8](https://github.com/joyent/mdb_v8)
+- [node-heapdump](https://github.com/bnoordhuis/node-heapdump)
+- [llnode](https://github.com/indutny/llnode)
+- [IBM IDDE](https://www.ibm.com/developerworks/java/jdk/tools/idde/)
+- [Snapshot Utils](https://github.com/bmeck/snapshot-utils)
+

docs/perf-events/README.md

@@ -0,0 +1,26 @@
+## Profiling for Node  
+- CPU Profiling
+  - V8 CPU Profiler: [v8/include/v8-profiler.h](https://github.com/v8/blob/master/include/v8-profiler.h)
+    - Accessible globally through `--prof` runtime flag, basic processing and display through `--prof-processor` runtime flag
+  - Intel vTune profiler. Accessible through `--enable-vtune-profiling` compile-time flag.
+
+- Heap Profiling
+  - V8 Heap Profiler: [v8/include/v8-profiler.h](https://github.com/v8/blob/master/include/v8-profiler.h)
+    - Heap memory usage stats are available through built-in 'v8' module.
+
+Name | Sponsor
+-----|--------
+[v8-profiler][] | StrongLoop
+[Chrome DevTools][] | Google
+
+[v8-profiler]: https://github.com/node-inspector/v8-profiler
+[Chrome DevTools]: https://github.com/ChromeDevTools/devtools-frontend
+
+### Stack Analysis  
+- [0x](https://github.com/davidmarkclements/0x)
+- [StackVis](https://github.com/joyent/node-stackvis)
+
+## Docs  
+[guides/simple-profiling](https://nodejs.org/en/docs/guides/simple-profiling/)
+[paulirish/automated-chrome-profiling](https://github.com/paulirish/automated-chrome-profiling)
+