[AC-5150] Disparity in Modules.TouchId documentation and example code

The documentation(http://docs.appcelerator.com/platform/latest/#!/api/Modules.TouchId.KeychainItem) does not show a reset method but does show a delete method. The example code for the module ti.touchid(2.1.2) shows an example using reset instead of delete. This seems counter-intuitive to the docs above. As a secondary point, when creating keychain items there are optional keys which aren't required. It is unclear that if you don't set an optional what the defaults would be. This could be quite integral to the security of an application and/or could hinder access also.