GitHub issue template should explain how to obtain `messages.log`

[Marcono1234]

Is your feature request related to a problem? Please describe. The GitHub issue template currently only says: https://github.com/oracle/visualvm/blob/0c39bd63aeb5134fa400021509b5bf85192efdd7/.github/ISSUE_TEMPLATE/bug_report.md?plain=1#L24

It might not be clear to users where to find this file.

Describe the solution you'd like Extend the GitHub issue template to mention that the file can be obtained from "Help" > "About" > "Logfile" (or mention the default file path where it is stored).