docs: update README

CHANGELOG.md

 # Changelog
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CONTRIBUTING.md

-# Contributing
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README.md

-# psimpy
+# Description
 
-Predictive and probabilistic simulation tools.
+`PSimPy` (Predictive and probabilistic simulation with Python) implements
+a Gaussian process emulation-based framework that enables systematically and
+efficiently inverstigating uncertainties associated with physics-based models
+(i.e. simulators).
 
 ## Installation
 
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 ## Usage
 
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-## Contributing
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 ## License
 
-`psimpy` was created by Hu Zhao. It is licensed under the terms of the MIT license.
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+`PSimPy` was created by Hu Zhao at the Chair of Methods for Model-based
+Development in Computational Engineering. It is licensed under the terms of
+the MIT license.
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