Documentation Update: Disabling Detectors

[artemdinaburg]

All detectors are on by default, and some of them are slow. We should provide some documentation about disabling detectors to improve manticore's speed.

After profiling Manticore runs on some Ethereum benchmarks, a lot of the time (say 50% or so) is spent in detectors. Some detectors, like uninitialized-memory have a particularly large impact, and should not be enabled unless we are looking for those bugs.

Some discussion led to the following command line invocations as being considerably faster for many Ethereum use-cases:

--exclude-all --evm.oog ignore or even --exclude-all --txnoether --evm.oog ignore

We should at least document these somewhere or perhaps even make one of the the default setting.