Update docs

docs/source/training_a_model.md

@@ -33,7 +33,7 @@
     If you like to run a multi-gpu training using DDP back-end,
 
     ```bash
-    $ CUDA_VISIBLE_DEVICES="0, 1, 2" python TTS/bin/distribute.py --script <path_to_your_script>/train_glowtts.py
+    $ CUDA_VISIBLE_DEVICES="0, 1, 2" python -m trainer.distribute --script <path_to_your_script>/train_glowtts.py
     ```
 
     The example above runs a multi-gpu training using GPUs `0, 1, 2`.

docs/source/tutorial_for_nervous_beginners.md

@@ -56,7 +56,7 @@ A breakdown of a simple script that trains a GlowTTS model on the LJspeech datas
     - Run multi-gpu training.
 
         ```bash
-        CUDA_VISIBLE_DEVICES=0,1,2 python TTS/bin/distribute.py --script train.py
+        CUDA_VISIBLE_DEVICES=0,1,2 python -m trainer.distribute --script train.py
         ```
 
 ### CLI Way