Summary: Turbo AI adds direct PDF upload example

Why It Matters: This change makes it clearer how users can start using Turbo AI with their own files.

What Changed:

• The text "10% Processing your PDF..." was removed.
• The text "Lec 5: Cellular Bio.pdf Drop your PDF here" was added.
• All URLs changed from https://www.turbolearn.ai/ to https://turbolearn.ai/.
• The "Cookie Settings" section was moved lower on the page.