update readme

Author: nahid

README.md

@@ -137,6 +137,10 @@ Following API examples are shown based on the sample JSON data given [here](exam
 * [find](#findpath)
 * [at](#atpath)
 * [from](#frompath)
+* [then](#then)
+* [collect](#collect)
+* [json](#json)
+* [import](#import)
 * [where](#wherekey-op-val)
 * [orWhere](#orwherekey-op-val)
 * [whereIn](#whereinkey-val)
@@ -155,12 +159,23 @@ Following API examples are shown based on the sample JSON data given [here](exam
 * [first](#first)
 * [last](#last)
 * [nth](#nthindex)
+* [column](#column)
+* [implode](#implode)
 * [exists](#exists)
 * [groupBy](#groupbyproperty)
 * [sort](#sortorder)
 * [sortBy](#sortbyproperty-order)
 * [reset](#resetdata)
 * [copy](#copy)
+* [toJson](#tojson)
+* [keys](#keys)
+* [values](#values)
+* [filter](#filter)
+* [transform](#transform)
+* [each](#each)
+* [pipe](#pipe)
+* [macro](#macro)
+* [chunk](#chunk)
 
 ### `fetch()`