added plinko finite state machine and workflow orchestrator (#4922)

Co-authored-by: Steve Hebert <[email protected]>

README.md

@@ -576,6 +576,7 @@ additional ordered map implementations.
 - [hide](https://github.com/emvi/hide) - ID type with marshalling to/from hash to prevent sending IDs to clients.
 - [hilbert](https://github.com/google/hilbert) - Go package for mapping values to and from space-filling curves, such as Hilbert and Peano curves.
 - [hyperloglog](https://github.com/axiomhq/hyperloglog) - HyperLogLog implementation with Sparse, LogLog-Beta bias correction and TailCut space reduction.
+- [plinko](https://github.com/shipt/plinko) - A finite state machine and workflow orchestrator that compiles for fast execution, easy debugging, auto-generated documentation. Includes advanced features such as side-effect hooks. 
 - [quadtree](https://github.com/s0rg/quadtree) - Generic, zero-alloc, 100%-test covered quadtree.
 - [slices](https://github.com/srfrog/slices) - Functions that operate on slices; like `package strings` but adapted to work with slices.
 - [slices](https://github.com/twharmon/slices) - Pure, generic functions for slices.