Migrate to new issue templates workflow (#6291)

See https://help.github.com/en/github/building-a-strong-community/about-issue-and-pull-request-templates

.github/ISSUE_TEMPLATE/bug_report.md

@@ -1,3 +1,11 @@
+---
+name: Bug report
+about: Create a bug report to help us improve
+title: ''
+labels: ''
+assignees: ''
+
+---
 
 * KOReader version:
 * Device:
@@ -20,7 +28,4 @@ Android won't have a crash.log file because Google restricts what apps can log,
 
 Please try to include the relevant sections in your issue description.
 You can upload the whole `crash.log` file on GitHub by dragging and
-dropping it onto this textbox, or you can use one of these paste services.
+dropping it onto this textbox.
-Please don't forget to set a high expiration date if you do.
-https://pastebin.com https://slexy.org https://paste2.org https://fpaste.org
-http://ix.io https://paste.kde.org https://paste.debian.net.