docs(dashboards): add documentation for copying widgets between dashboards (#15930)

Co-authored-by: inkeep[bot] <257615677+inkeep[bot]@users.noreply.github.com>
Co-authored-by: Matt Pua <matt.p@posthog.com>

Author: inkeep[bot]

contents/docs/product-analytics/dashboards.mdx

@@ -131,6 +131,17 @@ Each insight card on a dashboard has a **⋯** menu with quick visualization tog
 
 These options require editor access to the insight.
 
+### Moving and copying widgets
+
+You can move or copy insight cards and text cards to other dashboards from the **⋯** menu on each card:
+
+- **Move to** - Moves the widget from the current dashboard to another dashboard. It's removed from the current dashboard.
+- **Copy to** - Copies the widget to another dashboard while keeping it on the current dashboard.
+
+Both options require editor access to the target dashboard.
+
+When you copy an insight, it's the same underlying insight appearing on multiple dashboards (as [noted above](#creating-a-new-dashboard)). Any changes to the insight are reflected everywhere it appears. This is different from duplicating an insight, which creates an independent copy.
+
 ### Adding text cards
 
 Click the dropdown on the **Add...** button and select **Text card** to add a text card to your dashboard.