README.md: show afl-gcc as intel only
| Feature/Instrumentation | afl-gcc | llvm_mode | gcc_plugin | qemu_mode | unicorn_mode |
| ----------------------- |:-------:|:---------:|:----------:|:----------------:|:------------:|
- | NeverZero | x | x(1) | (2) | x | x |
+ | NeverZero | x86[_64]| x(1) | (2) | x | x |
| Persistent mode | | x | x | x86[_64]/arm[64] | x |
| LAF-Intel / CompCov | | x | | x86[_64]/arm[64] | x86[_64]/arm |
| CmpLog | | x | | x86[_64]/arm[64] | |
