Update README.md

README.md

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 [![Build Status](https://travis-ci.com/loostrum/arts_tools.svg?branch=master)](https://travis-ci.com/loostrum/arts_tools)  
 Processing scripts for Apertif Radio Transient System data
 
+## Requirements
+* Python >= 3.6
+* Numpy >= 1.17
+
+## Installation
+`pip install arts_tools`
+
 ## Fixing archival FITS files
 FITS files retrieved from the Apertif Long-Term Archive (ALTA) from before 2020/04/08 can be made readable using `arts_fix_fits`. Four fixes are applied:
 1. The NAXIS2 value in the header is changed from zero to the correct value