Add a new "Gotchas sections" subsection to "Patterns for effective
instructions" in the best practices guide. Covers what a gotcha is
(environment-specific facts that defy reasonable assumptions), how to
structure them (problem/correction pairs), and why they belong directly
in `SKILL.md` rather than a separate reference file.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>