Re-add desync_report.md

This file was inadvertently deleted so adding back.

Author: derekbekoe

.github/ISSUE_TEMPLATE/desync_report.md

@@ -0,0 +1,40 @@
+---
+name: Desync
+about: Please provide information about the desync you encountered to help us resolve the problem
+---
+
+**Before filing a new issue, check that it's not already captured by one in [this list](https://github.com/MicrosoftDocs/live-share/issues/4260)**
+
+**Product and Version** [VS/VSCode]:
+**OS Version** [macOS/Windows/Linux]:
+**Live Share Extension Version**:
+**Target Platform or Language** [e.g. Node.js]:
+
+**What were you doing when you encountered the desync?**
+
+**How often have you encountered desyncs?**
+
+**Do the host and the guest have the same contents?**
+
+*If yes, there's no need to answer the following questions*
+
+If you are using VS Code, the following will provide helpful information.
+
+On both the host and the guest:
+- Enable the `liveshare.diagnosticMode` setting
+- Open the file that's out of sync
+- Run the `liveshare.getCoeditingInformation` command (`ctrl+shift+p` to open the command palette, then search for "Get co-editing information") and paste the results below
+
+**Host co-editing information:**
+
+**Guest co-editing information:**
+
+To check that messages are being sent and received, open the Output view (`ctrl+shift+u`) and select "Visual Studio Live Share Coediting" from the dropdown. Type a character. On the sending end, you should see output like:
+```
+[2020-12-10 23:51:25.351 ] Post message: {"messageType":"textChange","changes":[{"length":0,"newText":"a","start":400}],"changeServerVersion":12,"clientId":24,"fileName":"/src/foo.txt","time":1607644285349,"sendId":16}
+```
+On the receiving end, you should see output like:
+```
+[2020-12-10 23:51:27.713 ] Receive message: {"context":{"GuestSessionId":"31","IsOwner":"False"},"sourceId":"Coauthoring","eventId":45,"jsonContent":"{"messageType":"textChange","changes":[{"length":0,"newText":"a","start":400}],"changeServerVersion":12,"clientId":24,"fileName":"/src/foo.txt","time":1607644427514,"sendId":25}","time":1607644427713}
+```
+**Are messages being sent and received?**