Add explainers for assembly instructions for easier reading

[egonelbre]

Many instructions can be rewritten to be clearer for people, e.g.

MOV (R2), R1 ==> R1 := memory[R2]

ADDQ $1, R1 ==> R1 := R1 + 1

LEAQ 0(R1)(R2*4), R3 ==> R3 := R1 + R2 * 4

FMADDS F0, F2, F1, F2  ==> F2 := F0*F1 + F2

It doesn't need to be comprehensive, however if there was a list of substitutions then people can add new ones as the need arises.