[ddc] Add web hot reload issue template.

This is a temporary template that we will use to capture feedback for stateful hot reload on the web.

Once hot reload is fully enabled and it is in a stable state, we will remove this template and any further issues discovered in the future will be filed via the normal Web issue filing template.

Change-Id: I462cb20898953f08335010f383574096315078c8
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/409020
Reviewed-by: Kevin Moore <kevmoo@google.com>
Commit-Queue: Nate Biggs <natebiggs@google.com>

.github/ISSUE_TEMPLATE/6_web_hot_reload.md

@@ -0,0 +1,21 @@
+---
+name: Report an issue related to Dart Web Stateful Hot Reload
+about: >-
+  Create an issue specific to the Stateful Hot Reload feature available via the
+  Dart web development compiler (DDC).
+labels: area-web, web-hot-reload, web-dev-compiler
+assignees: nshahan, biggs0125
+---
+Begin by checking the [web-hot-reload](https://github.com/dart-lang/sdk/labels/web-hot-reload) label to ensure this is not a known issue.
+
+If a similar issue has not been filed yet, use this template to file a new issue with the correct labels.
+
+If the issue you are experiencing presents itself in Flutter, please file an issue here in the Dart repository. We will forward any Flutter-specific issues to the Flutter repository as needed.
+
+Note: Hot reload rejections are expected errors that occur when a change is made that prevents the compiler from generating valid hot reload code. If you encounter such a rejection you must either undo the change to reload or perform a full hot restart.
+
+Where possible, please include any relevant code snippets and previous versions of the code prior to hot reloading that may have contributed to the discovered issue.
+
+If you are using a published SDK (e.g. on the dev channel) please include the version emitted by `dart --version`. If you're using a locally built SDK, please include the git commit of your local Dart checkout.
+
+Thank you for helping improve hot reload on the web!