[VOICEVOX] added new voices and short comment (#128)

added some voices that hadn't been before, and wrote a comment on how to
use VOICEVOX.

src/ts/storage/database.ts

@@ -322,6 +322,7 @@ export interface character{
     ttsMode?:string
     ttsSpeech?:string
     voicevoxConfig?:{
+        speaker?: string
         SPEED_SCALE?: number
         PITCH_SCALE?: number
         INTONATION_SCALE?: number