docs(readme) add exec

README.md

@@ -1,7 +1,35 @@
-Util.io [![NPM version][NPMIMGURL]][NPMURL]
-=======
+# Util.io [![NPM version][NPMIMGURL]][NPMURL]
 [NPMIMGURL]:                https://badge.fury.io/js/util.io.png
 [NPM_INFO_IMG]:             https://nodei.co/npm/util.io.png?downloads=true&&stars
 [NPMURL]:                   https://npmjs.org/package/util.io "npm"
 
-Util.io - utilites for vanila js
+Util.io - utilites for vanila js. Consist of nice set of functions that works in node and browser.
+
+## Install
+For node:
+```
+npm i util.io
+```
+For browser:
+```html
+<script src="lib/util.js"
+```
+
+## Api
+### exec
+Check is parameter is function, if it's - executes it with given parameters
+
+Was:
+```js
+function(callback, p1, p2, pN) {
+    if (typeof callback === 'function')
+        callback(p1, p2, pN);
+}
+```
+
+Now
+```js
+function(callback, p1, p2, pN) {
+    Util.exec(callback, p1, p2, pN);
+}
+```