clearer tts instruction

inference_speech_editing.ipynb

@@ -39,6 +39,19 @@
     "from models import voicecraft\n"
    ]
   },
+  {
+   "cell_type": "code",
+   "execution_count": null,
+   "metadata": {},
+   "outputs": [],
+   "source": [
+    "# install MFA models and dictionaries if you haven't done so already\n",
+    "!source ~/.bashrc && \\\n",
+    "    conda activate voicecraft && \\\n",
+    "    mfa model download dictionary english_us_arpa && \\\n",
+    "    mfa model download acoustic english_us_arpa"
+   ]
+  },
   {
    "cell_type": "code",
    "execution_count": 3,