do anyone know where i can find material on risc5 isa

RISCV.org?

please note that there is an older project called RISC5 that is completely unrelated to RISC-V. The older project is part of the Oberon language implementation

The github instruction-set manual is probably the best bet - it is updated periodically. It can be found here: https://github.com/riscv/riscv-isa-manual. The book by David Patterson and Andrew Waterman is also awesome and relatively cheap: I believe there is one free em português on their website too (http://riscvbook.com)!