Adding delayed response message for holidays (#276)

Author: lahirumaramba

.github/ISSUE_TEMPLATE/bug_report.md

@@ -7,6 +7,8 @@ assignees: ''
 
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+**Thank you for submitting your issue. We are operating at reduced capacity from Dec 18 2020 to Jan 4 2021. Please expect delayed responses. For more urgent requests please reach us via our  support channels https://firebase.google.com/support**
+
 ### [READ] Step 1: Are you in the right place?
 
   * For issues related to __the code in this repository__ file a Github issue.