bug_report.md: Add more guidance and hints; use comments and headings
bug_report.md: Add more guidance and hints; use comments and headings

The HTML comments are inspired by the HA template. They can be erased or
kept in the issue, but won't appear when viewing the issue.

https://raw.githubusercontent.com/home-assistant/core/dev/.github/ISSUE_TEMPLATE.md

Descriptions, examples and links were added to provide further guidance.

dresden-elektronik/deconz-rest-plugin,dresden-elektronik/deconz-rest-plugin,dresden-elektronik/deconz-rest-plugin,dresden-elektronik/deconz-rest-plugin,dresden-elektronik/deconz-rest-plugin