Added README for `hacks/` that one-sentence-summarizes the hacks contained within.

[screensavers] / hacks / README.md

OverviewHacks in this directory include:WolframAutomata: One-dimensional cellular automata simulator.NEDsim: Blinkenlights frontpanel for NED, a 32-bit RISC stack machine.See individual project READMEs for further details.