Add subscript to issue templates (open-telemetry#3576)

Co-authored-by: otelbot <[email protected]>

Author: opentelemetrybot

.github/ISSUE_TEMPLATE/bug_report.md

@@ -17,3 +17,5 @@ What did you see instead?
 
 **Additional context**
 Add any other context about the problem here.
+
+<sub>**Tip**: [React](https://github.blog/news-insights/product-news/add-reactions-to-pull-requests-issues-and-comments/) with 👍 to help prioritize this issue. Please use comments to provide useful context, avoiding `+1` or `me too`, to help us triage it. Learn more [here](https://opentelemetry.io/community/end-user/issue-participation/).</sub>

.github/ISSUE_TEMPLATE/feature_request.md

@@ -17,3 +17,5 @@ Which alternative solutions or features have you considered?
 
 **Additional context**
 Add any other context about the feature request here.
+
+<sub>**Tip**: [React](https://github.blog/news-insights/product-news/add-reactions-to-pull-requests-issues-and-comments/) with 👍 to help prioritize this issue. Please use comments to provide useful context, avoiding `+1` or `me too`, to help us triage it. Learn more [here](https://opentelemetry.io/community/end-user/issue-participation/).</sub>