UI: Fix document title not updating

[lonyele]

Issue: #866

What I did

I extracted storyInfo and passed it to <Helmet /> so that it can refresh document title.

How to test

• Is this testable with Jest or Chromatic screenshots? Should later add tests to lib/ui package
• Does this need a new example in the kitchen sink apps? No
• Does this need an update to the documentation? No

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[lonyele]

@ndelangen I should have explained more context for better code review experience, I can't really spend much time on opensource right now...(recruiting process...)
Just more info, It would have been better if I could find why selected is undefined and fix this part. Instead, I used storiesHash for finding the story info we are looking for. The reason for this implementation is that as I know of storiesHash is the core data structure and selected is some derived state from clicking or routing. I simply thought using this core data is more reliable in the long run.

[ndelangen]

@lonyele thanks for the clarification.

I tested the solution and it worked. I'll revisit the code and the reason why we had to do this at a later stage. Thanks for the time you've invested already. You're welcome back anytime! 💯 👏