docs(skills): simplify plugin creator deeplink shape

[efrazer-oai]

Summary

Plugin Creator now documents the shorter local-plugin handoff URL that the app can interpret directly. #22221 teaches the skill to end marketplace-backed creation flows with named View and Share links; this follow-up updates those examples so the skill only emits the normalized plugin name, the absolute marketplace path, and optional share mode.

The documented shape is:

codex://plugins/<normalized-plugin-name>?marketplacePath=<absolute-marketplace-json-path>
codex://plugins/<normalized-plugin-name>?marketplacePath=<absolute-marketplace-json-path>&mode=share

The skill text now states exactly where the normalized plugin name belongs, exactly where the absolute marketplace path belongs, and that it should not add pluginName or hostId query parameters.

Testing

Tests: plugin-creator skill validation.