chore: remove irrelevant doc from BitmapWidgetRenderingSupport handler [skip ci] (#356)

This is an old doc from the internal days that has no relevance nowadays.

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Author: Eugene Cheung

assets/BitmapWidgetRenderingSupport/index.js

@@ -8,11 +8,9 @@ const DOCS = `
           Param | Description
           ---|---
           **graph** | The graph definition. Use the parameters from the **Source** tab in CloudWatch Console's **Metrics** page.
-          **useMonitorPortal** (default = true) | Flag indicating whether we want to use MonitorPortal to render the graph. False will switch to CloudWatch API.
 
           ### Example parameters
           \`\`\` yaml
-          useMonitorPortal: boolean
           graph:
             view: timeSeries
             metrics: