fix: Change Github issue template

Change the issue template so that it is about Grails
and not Micronaut

Resolves grails#290

.github/ISSUE_TEMPLATE/bug_report.md

@@ -10,7 +10,7 @@ assignees: ''
 Thanks for reporting an issue, please review the task list below before submitting the
 issue. Your issue report will be closed if the issue is incomplete and the below tasks not completed.
 
-NOTE: If you are unsure about something and the issue is more of a question a better place to ask questions is on Stack Overflow (http://stackoverflow.com/tags/micronaut) or Gitter (https://gitter.im/micronautfw/). DO NOT use the issue tracker to ask questions.
+NOTE: If you are unsure about something and the issue is more of a question a better place to ask questions is on Stack Overflow (http://stackoverflow.com/tags/grails) or Slack (https://slack.grails.org/). DO NOT use the issue tracker to ask questions.
 
 ### Description
 
@@ -40,7 +40,7 @@ Tell us what happens instead
 ### Environment Information
 
 - **Operating System**: TODO
-- **Micronaut Version:** TODO
+- **Grails Version:** TODO
 - **JDK Version:** TODO
 
 ### Example Application