number notebooks, fix figure caption formatting, get rid of duplicate save model

Author: Yara Mohajerani

MachineLearning_NeuralNetworks_Intro.ipynb renamed to 01_MachineLearning_NeuralNetworks_Intro.ipynb

@@ -58,12 +58,11 @@
     "\n",
     "\n",
     "![Neural network generic example fromw ww.astroml.org](https://www.astroml.org/_images/fig_neural_network_1.png)\n",
-    "<sub>Schematic from [AstroML](https://www.astroml.org/book_figures/chapter9/fig_neural_network.html#book-fig-chapter9-fig-neural-network)\n",
+    "<sub>Schematic from [AstroML](https://www.astroml.org/book_figures/chapter9/fig_neural_network.html#book-fig-chapter9-fig-neural-network)</sub>\n",
     "    \n",
     "    Figure produced by code under BSD license authored by Jake VanderPlas & Brigitta Sipocz.\n",
     "    The figure produced by this code is published in the textbook \"Statistics, Data Mining, and Machine Learning in Astronomy\" (2019)\n",
-    "    For more information, see http://astroML.github.com\n",
-    "</sub>"
+    "    For more information, see http://astroML.github.com"
    ]
   },
   {