update comments in log moudule

[Gris333]

What problem were solved in this pull request?

Issue Number: close #551

Problem:

• The original comment for Log::operator<< incorrectly stated that it "won't output header information" (like function, file, line, etc.).
• However, the actual implementation calls Log::out(), which internally uses LOG_HEAD macro to print full header info (timestamp, PID/TID, context, function, file, line).

This mismatch can mislead users into thinking operator<< only writes raw message content, potentially causing confusion or misuse.

What is changed and how it works?

Updated the Doxygen-style comment above Log::operator<< template function in src/common/log/log.h.

New comment clearly states:

• operator<< does output standard header info (time, pid/tid, ctx, func, file, line).
• If user wants to customize or suppress headers, they should use output() / out() methods directly.

Other information

No code logic changed — only comments correction.

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[Copilot]

Pull request overview

This pull request corrects misleading documentation in the Log module. The original comment for Log::operator<< incorrectly stated that it "won't output header information" when in fact it does emit full header details (timestamp, PID/TID, context, function, file, line) via the LOG_HEAD macro, just like other LOG_* macros.

Key Changes:

• Updated the Doxygen comment for Log::operator<< to accurately reflect that it outputs standard log headers
• Clarified when users should use output() method for custom header handling

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