Fix formatting in README

Update README.md

Enhance README with project details and benchmarks

Rename customtestpow.c to custom_test_pow.c

Rename mathtestpow.c to math_test_pow.c

test code using for loop to find power (x^n) of a no.

test code using math library power instruction

test code using custom built POW

Fix formatting

Add custom POW instruction support

Implement custom MOD instruction

Add project description for RISCV instruction implementation

Initial commit