docs(plugins): fill up rest of manifest and hooks reference + creating a plugin

docs/package.json

docs/pnpm-lock.yaml

docs/src/content/docs/en/plugins/create.mdx

docs/src/content/docs/en/plugins/helpers.mdx

docs/src/content/docs/en/plugins/hooks.mdx

docs/src/content/docs/en/plugins/index.mdx

docs/src/content/docs/en/plugins/manifest.mdx

modules/Plugins/Manifest/Field.php

modules/Plugins/Manifest/Fields.php

modules/Plugins/Manifest/manifest.schema.json

...odules/Plugins/mocks/manifests/manifest-full-invalid.json

.../modules/Plugins/mocks/manifests/manifest-full-valid.json