docs: Update contribution guidelines and issue template regarding issue

reproductions

Author: mmalerba

.github/ISSUE_TEMPLATE/bug.yml

@@ -28,10 +28,15 @@ body:
     attributes:
       label: Reproduction
       description: |
-        **Use StackBlitz to reproduce your issue:**
-        - [Components](https://stackblitz.com/fork/components-issue)
-        - [Harnesses](https://stackblitz.com/fork/harness-issue)
+        Use StackBlitz to reproduce your issue:
+        - [Components StackBlitz starter](https://stackblitz.com/fork/components-issue)
+        - [Harnesses StackBlitz starter](https://stackblitz.com/fork/harness-issue)
+
+        Issues that do not include a StackBlitz (or other REPL) reproduction link will be closed.
+        If it is not possible to create a StackBlitz reproduction for your issue, please explain why
+        and include any other information you can to help the team reliably reproduce the issue.
       value: |
+        StackBlitz link: 
         Steps to reproduce:
         1. 
         2.

CONTRIBUTING.md

@@ -31,9 +31,13 @@ If you would like to chat about the question in real-time, you can reach out via
 
 ## <a name="issue"></a> Found an Issue?
 If you find a bug in the source code or a mistake in the documentation, you can help us by
-[submitting an issue](#submit-issue) to our [GitHub Repository][github]. Including an issue
-reproduction (via CodePen, JsBin, Plunkr, etc.) is the absolute best way to help the team quickly
-diagnose the problem. Screenshots are also helpful.
+[submitting an issue](#submit-issue) to our [GitHub Repository][github]. 
+
+For bugs, including an issue reproduction (via your preferred REPL: StackBlitz, CodePen, JsBin,
+Plunkr, etc.) is the absolute best way to help the team quickly diagnose the problem. Issues that do
+not include a REPL reproduction will be closed. If a REPL reproduction is not possible for your
+issue, please explain why and include any other information that may be helpful in debugger (link to
+a repo, error messages, screenshots, etc.)
 
 You can help the team even more and [submit a Pull Request](#submit-pr) with a fix.