Update README.md: short OSMD description

Say what OSMD does in first sentence

README.md

@@ -12,7 +12,7 @@
 
 https://www.opensheetmusicdisplay.org/
 
-OpenSheetMusicDisplay is the missing link between MusicXML and VexFlow. Built upon many years of experience in both sheet music interactivity and engraving, it is the perfect solution for app developers seeking to build digital sheet music services.
+OpenSheetMusicDisplay renders MusicXML sheet music in the browser. It is the missing link between MusicXML and VexFlow. Built upon many years of experience in both sheet music interactivity and engraving, it is the perfect solution for app developers seeking to build digital sheet music services.
 
 MusicXML is the de facto standard for sharing sheet music on the internet. VexFlow is widely used for rendering sheet music. It features an extensive note sign library attributable to its open source nature.