Correct and clarify rounding mode descriptions in docs #3243

Our documentation currently describes division, remainder, and rounding behaviors inconsistently, sometimes mixing them with Python/C++ semantics. The TVM has unique implementations for ceil and round rounding modes (see TVM.pdf specification, section 1.5.6), differing from common languages and causing confusion for developers.

Task:

• Review all documentation sections related to division, remainders, and rounding operations.
• Update all descriptions, explanations, and examples to precisely match the definitions provided in the TVM specification (tvm.pdf §1.5.6), especially clarifying differences in the ceil and round rounding modes.
• Ensure all examples clearly reflect TVM's actual behavior rather than assumptions from Python, C++, or other common languages.