correcting name of keepMicrophone param

Author: nfriedly

README.md

@@ -83,7 +83,7 @@ The core of the library is the [RecognizeStream] that performs the actual transc
 ### [`.recognizeMicrophone({token})`](http://watson-developer-cloud.github.io/speech-javascript-sdk/master/module-watson-speech_speech-to-text_recognize-microphone.html) -> Stream
 
 Options: 
-* `keepMic`: if true, preserves the MicrophoneStream for subsequent calls, preventing additional permissions requests in Firefox
+* `keepMicrophone`: if true, preserves the MicrophoneStream for subsequent calls, preventing additional permissions requests in Firefox
 * `mediaStream`: Optionally pass in an existing media stream rather than prompting the user for microphone access.
 * Other options passed to [RecognizeStream]
 * Other options passed to [SpeakerStream] if `options.resultsbySpeaker` is set to true