added abs to readme

.vscode/settings.json

@@ -1,3 +1,11 @@
 {
-    "eslint.enable": false
+    "eslint.enable": false,
+    "spellright.language": [
+        "en"
+    ],
+    "spellright.documentTypes": [
+        "markdown",
+        "latex",
+        "plaintext"
+    ]
 }

README.md

@@ -21,13 +21,15 @@
 <!-- DON'T EDIT THIS SECTION, INSTEAD RE-RUN doctoc TO UPDATE -->
 ## Contents
 
+  - [Contributors Welcome!](#contributors-welcome)
   - [Installation](#installation)
     - [Usage](#usage)
   - [Operations](#operations)
     - [bigDecimal(number)](#bigdecimalnumber)
     - [getValue()](#getvalue)
     - [getPrettyValue(number, digits, separator)](#getprettyvaluenumber-digits-separator)
     - [round(number, precision, roundingMode)](#roundnumber-precision-roundingmode)
+    - [abs(number)](#absnumber)
     - [floor(number)](#floornumber)
     - [ceil(number)](#ceilnumber)
     - [compareTo(number1, number2)](#comparetonumber1-number2)
@@ -143,6 +145,18 @@ var numRound1 = num.round(1, bigDecimal.RoundingModes.DOWN); // "123.6"
 var numRound2 = num.round(2, bigDecimal.RoundingModes.CEILING); // "123.66"
 ```
 
+### abs(number)
+Returns the absolute value of a number.
+```javascript
+var n1 = bigDecimal.abs(12.8) // "12.8"
+var n2 = bigDecimal.abs(-12.3) // "12.3"
+```
+The instance returns the result as new `bigDecimal`
+```javascript
+var n1 = new bigDecimal(12.8).abs() // bigDecimal(12.8)
+var n2 = new bigDecimal(-12.3).abs() // bigDecimal(-12.3)
+```
+
 ### floor(number)
 Returns the whole number nearest but not greater than the input number.
 ```javascript