Add development notice

[scoltman]

• [ ] Add a notice with the follow text: "This tool is currently in development. Please verify all responses you receive. We welcome your feedback and would love to hear if the tool contributes to any published fact checks."
• [ ] text should be slightly smaller that 1em
• [ ] everything should be centrally aligned
• [ ] make sure "videos" in made header doesn't wrap onto a second line and medium screen width