DOC: fix links to Jupyter logo

Author: mgeier

doc/code-cells.ipynb

@@ -252,7 +252,7 @@
    "metadata": {},
    "outputs": [],
    "source": [
-    "Image(url='https://jupyter.org/assets/nav_logo.svg')"
+    "Image(url='https://jupyter.org/assets/homepage/main-logo.svg')"
    ]
   },
   {

doc/gallery/multiple-outputs.ipynb

@@ -48,7 +48,7 @@
    "source": [
     "from IPython.display import Image\n",
     "\n",
-    "display(Image(url='https://jupyter.org/assets/nav_logo.svg'))\n",
+    "display(Image(url='https://jupyter.org/assets/homepage/main-logo.svg'))\n",
     "print('Hello!')\n",
     "display(Image(filename='../images/notebook_icon.png'))\n",
     "display(Image(url='https://www.python.org/static/img/python-logo-large.png', embed=True))"

doc/markdown-cells.ipynb

@@ -364,9 +364,9 @@
     "    ![Python logo](images/python_logo.svg)\n",
     "Remote SVG images can also be used (and will be shown in the LaTeX output):\n",
     "\n",
-    "![Jupyter logo](https://jupyter.org/assets/main-logo.svg)\n",
+    "![Jupyter logo](https://jupyter.org/assets/homepage/main-logo.svg)\n",
     "\n",
-    "    ![Jupyter logo](https://jupyter.org/assets/main-logo.svg)"
+    "    ![Jupyter logo](https://jupyter.org/assets/homepage/main-logo.svg)"
    ]
   },
   {