adding contextualhelp spectrum docs link (#2979)

Author: matthewdeutsch

packages/@react-spectrum/contextualhelp/docs/ContextualHelp.mdx

@@ -34,7 +34,7 @@ keywords: [popover, field, input]
 <HeaderInfo
   packageData={packageData}
   componentNames={['ContextualHelp']}
-  sourceData={[]} />
+  sourceData={[ {type: 'Spectrum', url: 'https://spectrum.adobe.com/page/contextual-help/'} ]} />
 
 ## Example