Move diagnostics doc, add ETW directions.

Author: aluhrs13

diagnostics.md renamed to diagnostics/diagnostics.md

@@ -39,3 +39,16 @@ Navigate to `about:tracing`and use with the `Edge developer (navigation)` profil
 3. Grab all the files on disk for Edge - the below command will do the trick and create edgefiles.txt
 
 `dir /s /b "c:\Program Files (x86)\Microsoft\EdgeWebView\" > edgefiles.txt`
+
+## ETW Trace
+One of the best ways to help us understand when something is going wrong like failures to create WV2 or other unexpected behaviors is an [Event Tracing for Windows (ETW)](https://learn.microsoft.com/en-us/windows-hardware/test/wpt/event-tracing-for-windows) trace. This repo has a WV2 recording profile - [WebView2.wprp](WebView2.wprp) that includes the events that we find most useful. 
+
+ETW traces can get fairly large, so try to keep the amount of extra time spent when recording as small as possible. We also recommend closing any other apps using WV2 to make the trace more clear. Common apps using WV2 may include `widgets.exe`, `msteams.exe`, and Microsoft Office products.
+
+To get an ETW trace:
+1. Download [WebView2.wprp](WebView2.wprp) from this repo.
+2. In an elevated command prompt run `wpr -start WebView2.wppr -filemode` (wpr.exe is included in Windows)
+3. Reproduce the issue.
+4. In an elevated command prompt run `wpr -stop trace.etl "trace"`.
+
+ETW traces can contain sensitive information, if you're concerned with sharing one publicly in a GitHub issue, you can ask the WV2 developer you're working with for an email address to send to them privately.