update reference math round doc en

[PhilDaiguille]

This pull request includes updates to the reference/math/functions/round.xml file to enhance the documentation for the round function. The changes focus on updating the parameter types, adding new rounding modes, and providing more detailed examples.

Key changes include:

Documentation Updates:

• Updated the mode parameter to accept both int and RoundingMode types, with a new default value of RoundingMode::HalfAwayFromZero.
• Added a note to specify that some newly added rounding modes are only available in the RoundingMode enumeration.
• Included a new entry in the changelog to document the addition of four new rounding modes in version 8.4.0.

Examples:

• Added a comprehensive example demonstrating the usage of the RoundingMode enumeration with various rounding modes and their effects on different numbers.

[devnexen]

Fantastic !