Add track name support

docs/guide/reading-media-files.md

@@ -97,6 +97,9 @@ track.isAudioTrack(); // => boolean
 // Retrieve the track's language as an ISO 639-2/T language code.
 // Resolves to 'und' (undetermined) if the language isn't known.
 track.languageCode; // => string
+
+// A user-defined name for this track.
+track.name; // => string
 ```
 
 #### Codec information

docs/guide/writing-media-files.md

@@ -55,6 +55,7 @@ output.addVideoTrack(videoSource, {
 // This adds two audio tracks; one in English and one in German.
 output.addAudioTrack(audioSourceEng, {
 	language: 'eng', // ISO 639-2/T language code
+	name: 'Developer Commentary', // Sets a user-defined track name
 });
 output.addAudioTrack(audioSourceGer, {
 	language: 'ger',