Add converge

Based on http://ramdajs.com/docs/#converge

snippets/converge.md

@@ -0,0 +1,19 @@
+### converge
+
+Accepts a converging function and a list of branching functions and returns a function that applies each branching function to the arguments and the results of the branching functions are passed as arguments to the converging function.
+
+Use `Array.map()` and `Function.apply()` to apply each function to the given arguments.
+Use the spread operator (`...`) to call `coverger` with the results of all other functions.
+
+```js
+const converge = (converger, fns) => (...args) =>
+  converger(...fns.map(fn => fn.apply(null, args)));
+```
+
+```js
+const average = converge((a, b) => a / b, [
+  arr => arr.reduce((a, v) => a + v, 0),
+  arr => arr.length,
+]);
+average([1, 2, 3, 4, 5, 6, 7]); // 4
+```