v0.8 reference contradicts json schemas

[lukaszsamson]

1. Standard catalog id
   In schema: a2ui.org:standard_catalog_0_8_0
   In protocol spec: https://github.com/google/A2UI/blob/main/specification/v0_8/json/standard_catalog_definition.json
2. Component name difference
   In v0_8/json/standard_catalog_definition.json: CheckBox
   In docs/reference/components.md: Checkbox
3. docs/reference/components.md uses Material icon names like check_circle, but v0.8 catalog Icon.name enum uses check, error, etc.