minor modification to README

README.md

@@ -52,4 +52,4 @@ In this case, the interaction with the kernel is still at the release level, but
 For improved usability, all of the described functionality can be accessed through the command line by using the `zos` tool provided in the [zos-cli](https://github.com/zeppelinos/zos-cli) repository. This tool is useful for both users creating upgradeable projects using **zeppelin_os** and developers contributing releases of the standard library. A guide on its usage is provided in the linked repository.
 
 ### PickACard Example
-The `PickACard` game is provided as an example of usage of the kernel, together with mock `ERC721` library contracts. This last contracts showcase the simplicity of the modifications required to go from a standard off-chain library like [OpenZeppelin](https://github.com/OpenZeppelin/zeppelin-solidity/) to an on-chain, upgradeable stdlib of the type provided by **zeppelin_os**. In short, the constructor is replaced by an `initialize` method that takes care of initialzing the state variables, and is typically called upon creation of its upgradeability proxy. 
+The `PickACard` user app is provided as an example of usage of the kernel, together with mock `ERC721` library contracts. These last contracts showcase the simplicity of the modifications required to go from a standard off-chain library like [OpenZeppelin](https://github.com/OpenZeppelin/zeppelin-solidity/) to an on-chain, upgradeable stdlib of the type provided by **zeppelin_os**. As mentioned before, the constructor is replaced by an `initialize` method that takes care of initialzing the state variables, and is typically called upon creation of its upgradeability proxy. The `PickACard` app then uses the library through the kernel to get an implementation of the `ERC721` token.