fix: max_response_bytes is 2MB not 2MiB

[ninegua]

Description

The documentation (and example) for max_response_bytes is wrong. According to the interface spec and IC's implementation, the limit is 2MB, not 2MiB.

Checklist:

• The title of this PR complies with Conventional Commits.
• I have edited the CHANGELOG accordingly.
• I have made corresponding changes to the documentation.

[lwshang]

Thanks for catching this documentation issue regarding max_response_bytes!
The main branch is currently frozen, with active development happening on next. We plan to merge next into main after the "Best-Effort Responses" feature launches on mainnet. I'll make sure the documentation and example correctly specify 2MB (not 2MiB) on the next branch.