update readme with link to sage format specification

README.md

@@ -2,7 +2,7 @@
 
 [![Build Status](https://travis-ci.org/eCollect/taf-parser.svg?branch=master)](https://travis-ci.org/eCollect/taf-parser) [![Coverage Status](https://coveralls.io/repos/github/eCollect/taf-parser/badge.svg?branch=master)](https://coveralls.io/github/eCollect/taf-parser?branch=master) [![Known Vulnerabilities](https://snyk.io/test/github/eCollect/taf-parser/badge.svg)](https://snyk.io/test/github/eCollect/taf-parser) [![License: MIT](https://img.shields.io/badge/License-MIT-blue.svg)](/eCollect/pateka/blob/master/LICENSE)
 
-'Tagged Format' (TAF) files are files that can be used to export and import data sets used by the accounting system of Sage 50.
+'Tagged Format' (TAF) files are files that can be used to export and import data sets used by the accounting system of Sage 50 (more about this file format, supported tags and its specification can be found [here](https://github.com/eCollect/taf-parser/blob/master/docs/Sage50.TAF.Format.pdf)).
 
 The parser goes through a string content or a stream of data and detects one error at a time in the structure.
 
@@ -124,8 +124,6 @@ Writer.on('finish', () => {
 });
 ```
 
-## Knowledge base
-
 ## Licensing
 
 Copyright (c) 2018 eCollect AG.