[N/A] Update sipnet.output precision and doc

[Alomir]

Summary

• What: Quick tweak to increase output precision to minimum 4 digits, and update output doc

How was this change tested?

Smoke and unit tests; testOutputHeader updated.

Checklist

• PR title has the issue number in it ("[#] <concise description of proposed change>")
• Tests added/updated for new features (if applicable)
• Documentation updated (if applicable)
• docs/CHANGELOG.md updated with noteworthy changes
• Code formatted with clang-format (run git clang-format if needed)

[infotroph]

Thanks!