doc(plugins/introduction): update

source/plugins/introduction/metadata.yml

@@ -1,5 +1,12 @@
 name: "🙋 Introduction"
 category: github
+description: |
+  This plugin displays account bio or organization/repository description.
+
+  It is mostly intended for images that will be used outside of GitHub, since these informations are already displayed on GitHub.
+examples:
+  +for an user or an organization: https://github.com/lowlighter/metrics/blob/examples/metrics.plugin.introduction.svg
+  for a repository: https://github.com/lowlighter/metrics/blob/examples/metrics.plugin.introduction.repository.svg
 index: 22
 supports:
   - user