docs: add navigation links

source/plugins/calendar/metadata.yml

@@ -2,8 +2,8 @@ name: "📆 Calendar"
 category: github
 description: This plugin displays your commit calendar across several years
 examples:
-  +current year: https://github.com/lowlighter/metrics/blob/examples/metrics.plugin.calendar.svg
-  full history: https://github.com/lowlighter/metrics/blob/examples/metrics.plugin.calendar.full.svg
+  current year: https://github.com/lowlighter/metrics/blob/examples/metrics.plugin.calendar.svg
+  +full history: https://github.com/lowlighter/metrics/blob/examples/metrics.plugin.calendar.full.svg
 index: 25
 supports:
   - user