Link the calendar-year gallery example from the user guide

Developed with an AI assistant (Árbol, running Muse).

Author: scks1

docs/user_guide/triangle.ipynb

@@ -2372,6 +2372,26 @@
     "as their own classes.  Refer to `ValuationCorrelation` and\n",
     "`DevelopmentCorrelation` for additional information.\n",
     "\n",
+    "#### Examples\n",
+    "\n",
+    "::::{grid}\n",
+    ":gutter: 2\n",
+    "\n",
+    ":::{grid-item-card}\n",
+    ":columns: 4\n",
+    ":link: ../gallery/plot_valuation_correlation\n",
+    ":link-type: doc\n",
+    "**Calendar Year Tests**\n",
+    "```{image} ../images/plot_valuation_correlation.png\n",
+    "---\n",
+    "alt: Share of simulated triangles flagged by the per-diagonal and total tests\n",
+    "---\n",
+    "```\n",
+    "+++\n",
+    "{bdg-warning}`medium`\n",
+    ":::\n",
+    "::::\n",
+    "\n",
     "{cite}`mack1994`"
    ]
   },