Add comment details for nonce size

What does this MR do?

Add comments to ensure the context around nonce size is preserved to avoid any breaking changes in future. In the long run, once CI jobs for FIPS-Go are done, this scenarios should be covered as well.

TODO

• I added the Changelog trailer (e.g. Changelog: added) to the commits that need to be included in the changelog
• I added unit tests or they are not required
• I added acceptance tests or they are not required
• I added documentation (or it's not required)
• I followed code review guidelines
• I followed Go Style guidelines