The great refactor (#82)

source/plugins/followup/README.md

@@ -0,0 +1,22 @@
+### 🎟️ Follow-up of issues and pull requests
+
+The *followup* plugin displays the ratio of open/closed issues and the ratio of open/merged pull requests across all your repositories, which shows if they're well-maintained or not.
+
+<table>
+  <td align="center">
+    <img src="https://github.com/lowlighter/lowlighter/blob/master/metrics.plugin.followup.svg">
+    <img width="900" height="1" alt="">
+  </td>
+</table>
+
+#### ℹ️ Examples workflows
+
+[➡️ Available options for this plugin](metadata.yml)
+
+```yaml
+- uses: lowlighter/metrics@latest
+  with:
+    # ... other options
+    plugin_followup: yes
+```
+