added a bunch on reading/writing/playing audio

notebooks/get_good_at_ipython.ipynb

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  "metadata": {
   "name": "",
-  "signature": "sha256:3e47f19e4e3e474f96e45baef06f1047acd575cc2b8630e22591c25ead559a32"
+  "signature": "sha256:33b9ddca243fc0c15c4e4b11e131ddf070da9a9ea6bd8c3f08d02ecdcfd70b17"
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  "nbformat": 3,
  "nbformat_minor": 0,
@@ -50,6 +50,35 @@
       "To display the Help Menu, press `h`."
      ]
     },
+    {
+     "cell_type": "heading",
+     "level": 2,
+     "metadata": {},
+     "source": [
+      "Writing Text in Markdown"
+     ]
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "Markdown is a markup language that is a superset of HTML. The Markdown specification is found here: http://daringfireball.net/projects/markdown/"
+     ]
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "A cell may contain Python code or Markdown code. To convert any Python cell to a markdown cell, press `m`."
+     ]
+    },
+    {
+     "cell_type": "markdown",
+     "metadata": {},
+     "source": [
+      "For headings, we recommend that you use IPython's keyboard shortcuts. To change the text in a cell to a level-3 header, simply press `3`. For similar commands, press `h` to view the Help menu."
+     ]
+    },
     {
      "cell_type": "markdown",
      "metadata": {},