Make methods non-class. Add keychain prefix.

README.md

@@ -81,7 +81,7 @@ See the list of all available [access options](https://github.com/exchangegroup/
 
 ### Setting key prefix
 
-One can pass a `keyPrefix` argument when initializing a `KeychainSwift` object. The string passed in `keyPrefix` argument will be used as a prefix to the keys supplied in set, get, getData and delete methods. I use the prefixed keychain in test. This prevents the tests from changing the Keychain keys that are used when the app is launched manually.
+One can pass a `keyPrefix` argument when initializing a `KeychainSwift` object. The string passed in `keyPrefix` argument will be used as a prefix to the keys supplied in set, get, getData and delete methods. I use the prefixed keychain in tests. This prevents the tests from changing the Keychain keys that are used when the app is launched manually.
 
 Note that `clear` method still clears everything from the Keychain.