Some updates to the template more similar to the official Microsoft Word template

[yaoyao-liu]

Dear Prof. Luke Olson,

Thank you for creating this excellent LaTeX template! It has been incredibly helpful and well-designed.

While using the template, I made a few updates to align it more closely with the official Microsoft Word template:

• Changed the font from Montserrat to Source Sans.
• Updated the wordmark and logo to use the correct color, ensuring alignment with "Illini Blue."
• In the footer, removed "at" from "University of Illinois at Urbana-Champaign."

If you find these adjustments appropriate, I’d be happy to submit a pull request. You can review the changes here: https://github.com/yaoyao-liu/illinois-ischool-letterhead.

Thank you again for your efforts in creating and maintaining this resource!

Best regards,
Yaoyao