docs: improve README

[Copilot]

README had several accuracy and completeness gaps: wrong (unscoped) install command, unused badge definitions, a single tangled usage code block, and no API reference.

Changes

• Install command — corrected to @skitionek/route-with-dynamic-outlets
• Badges — moved all defined badges (build, npm, downloads, issues, codecov, semantic-release, commitizen) to the header where they're visible
• Badge URLs — updated npm/downloads URLs to the scoped package name
• Usage — split the single muddled block into four labelled steps: dynamic outlet component, route definition, nesting, and custom matcher; fixed invalid triple-backtick inside a fenced code block
• How it works — added a concise section describing the matcher-based mechanism (URL match → outlet diff → BehaviorSubject push → component subscription)
• API reference — added docs for createRouteWithDynamicOutlets, RouteWithDynamicOutlets, DynamicOutletRouteFactory, and OutletsMap with parameter tables and type signatures