readme: separate powerpc 32 and 64 bit in the support table
readme: separate powerpc 32 and 64 bit in the support table

andrewrk/zig,zig-lang/zig,zig-lang/zig,raulgrell/zig,raulgrell/zig,raulgrell/zig,raulgrell/zig,raulgrell/zig,zig-lang/zig,andrewrk/zig