Add ymlx (#1)

* Add ymlx

I wrote `ymlx` after being inspired by `fx` by copying then massaging.

* Update README.md

README.md

@@ -138,6 +138,7 @@ $ cat package.json | fx 'Object.keys(this.dependencies)'
 * [jsawk](https://github.com/micha/jsawk) – like awk, but for JSON
 * [json](https://github.com/trentm/json) – another JSON manipulating cli library
 * [jl](https://github.com/chrisdone/jl) – functional sed for JSON on Haskell
+* [ymlx](https://github.com/matthewadams/ymlx) - `fx`-like YAML cli processor
 
 ## License