add: journalct in auth logs linux roadmap

[zvdy]

This pull request includes updates to the documentation for reviewing authentication logs on Linux servers. The changes clarify the usage of different logging systems and provide additional resources for further learning.

Documentation updates:

• src/data/roadmaps/linux/content/105-server-review/101-auth-logs.md: Specified that auth logs are located in /var/log/auth.log or /var/log/secure for servers using syslog, and added instructions for using journalctl for servers using Journal.
• Added links to resources for further reading on the Journal native protocol and the Syslog protocol.

[github-actions]

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[kamranahmedse]

Thank you for the PR but we are intentionally keeping this content brief and focus on providing external resources for learning.