Add config.json, fix a readme typo

README.md

@@ -21,7 +21,7 @@ First of all, please install SpeechBrain with the following command (local insta
 
 ```bash
 pip install speechbrain
-pip install Transformers
+pip install transformers
 ```
 
 Please notice that we encourage you to read our tutorials and learn more about

config.json

@@ -0,0 +1,3 @@
+{
+    "speechbrain_interface": "GraphemeToPhoneme"
+}