Update README.md

Author: bjudkewitz

README.md

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 ![GitHub last commit](https://img.shields.io/github/last-commit/danionella/daio)
 
 # daio
-Video and data IO tools for Python.
+Speed-optimized, frame-accurate video and data IO tools for Python.
 
 Links: [API documentation](http://danionella.github.io/daio), [GitHub repository](https://github.com/danionella/daio)