Update README.md

README.md

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 [![Build Status](https://travis-ci.org/astromatic/sextractor.svg?branch=master)](https://travis-ci.org/astromatic/sextractor)
 [![Coverity Scan Build Status](https://scan.coverity.com/projects/sextractor/badge.svg)](https://scan.coverity.com/projects/sextractor "Coverity Badge")
 
-[SExtractor] stands for ``Source Extractor'': a software for extractingcatalog of sources from astronomical images.
+[SExtractor] stands for ``Source Extractor'': a software for extracting catalogs of sources from astronomical images.
 
 Check out the on-line [documentation], the [official web page], and the [user forum].