[WEBSITE] Add the new IFP address to the upgrade page

Summary: Right now the address is only readable in the code, which is not very convenient for pool operators.

Test Plan:

bundle exec jekyll serve --incremental

Check the address is correct and the code block looks good with various screen sizes.

Reviewers: #bitcoin_abc, bytesofman, Mengerian

Reviewed By: #bitcoin_abc, bytesofman, Mengerian

Subscribers: Mengerian, bytesofman

Differential Revision: https://reviews.bitcoinabc.org/D11376