Add credits section to README

Merge pull request #2 from lpcode808/patch-1

Update official Ralph plugin link in credits

Revise command steps and formatting in README

Refactor SKILL.md by removing license and comparison sections

Fix marketplace.json source path to start with ./

fix: Correct marketplace.json schema - owner as object

fix: Correct marketplace.json schema (owner + source)

fix: Add marketplace.json for plugin discovery

fix: Update installation instructions with correct plugin commands

feat: V2 - Quality-focused iteration with Voice DNA

Correct author name formatting in plugin.json

feat: Initial release of Ralph Wiggum Marketer plugin