docs(readme): reorganize for end users (#359)

* docs(readme): reorganize for end users

* docs(skill): -d accepts a database name or catalog

* docs(readme): keep the Claude Code plugin section verbatim

* docs(readme): runnable examples and links to the docs

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Co-authored-by: Eddie A Tejeda <669988+eddietejeda@users.noreply.github.com>

Author: eddietejeda