Add string encoding to README

Author: veigaribo

README.md

@@ -38,7 +38,7 @@ gyp ERR! stack Error: "pre" versions of node cannot be installed, use the --node
 
 ## Security Issues And Concerns
 
-> Per bcrypt implementation, only the first 72 bytes of a string are used. Any extra bytes are ignored when matching passwords. Note that this is not the first 72 *characters*. It is possible for a string to contain less than 72 characters, while taking up more than 72 bytes (e.g. a UTF-8 encoded string containing emojis).
+> Per bcrypt implementation, only the first 72 bytes of a string are used. Any extra bytes are ignored when matching passwords. Note that this is not the first 72 *characters*. It is possible for a string to contain less than 72 characters, while taking up more than 72 bytes (e.g. a UTF-8 encoded string containing emojis). If a string is provided, it will be encoded using UTF-8.
 
 As should be the case with any security tool, anyone using this library should scrutinise it. If you find or suspect an issue with the code, please bring it to the maintainers' attention. We will spend some time ensuring that this library is as secure as possible.