[Docs] explain how to pass context to runFlow and streamFlow

[markgoho]

Is your report related to a problem? Please describe.
How do we pass context to runFlow?

Is your report related to a suggestion/improvement? Please describe.
The /genkit/context page shows how to add context when calling a flow directly, e.g.

const summarizeHistory = ai.defineFlow(/* ... */);

const summary = await summarizeHistory(friend.uid, {context: {auth: currentUser}});

but when calling this from the front end, e.g.

// Angular component class
menuResource = resource({
  request: () => this.theme(),
  // where does the context go?
  loader: ({ request }) => runFlow<string>({ url: 'menu', input: request }),
});

Additional context
FYI, the word context in the template here makes it very difficult for issues pertaining to context