fix grammar

Thanks Min for correcting me every time, hopefully I'll become better in
writing English

docs/examples/notebooks/00_notebook_tour.ipynb

@@ -490,7 +490,7 b''
     {
      "cell_type": "markdown",
      "source": [
-      "Since IPython 0.13, image are embedded by default, for compatibility with QtConsole and the ability to still be displayed offline.",
+      "As of IPython 0.13, images are embedded by default for compatibility with QtConsole, and the ability to still be displayed offline.",
       "",
       "Let's look at the differences:"
      ]
@@ -505,7 +505,7 b''
       "# if kwarg `url` is given, the embedding is assumed to be false",
       "SoftLinked = Image(url='http://www.google.fr/images/srpr/logo3w.png')",
       "",
-      "# in every case embed can be override with the ` embed` kwarg",
+      "# In each case, embed can be specified explicitly with the `embed` kwarg",
       "# ForceEmbed = Image(url='http://www.google.fr/images/srpr/logo3w.png', embed=True)"
      ],
      "language": "python",
@@ -515,7 +515,7 b''
     {
      "cell_type": "markdown",
      "source": [
-      "Today's Google doodle, (at the time I created this notebook). Should also works in the Qtconsole.",
+      "Today's Google doodle, (at the time I created this notebook). This should also works in the Qtconsole.",
       "Drawback is that the saved notebook will be larger, but the image will still be present offline. 
      ]
     },
@@ -541,8 +541,8 b''
     {
      "cell_type": "markdown",
      "source": [
-      "Today's google doodle, visible only with an active internet connexion, that should be different from the previous one. This will not work on Qtconsole.",
-      "Notebook saved with this kind of image will be lighter and always reflect the curent version of the source, but the image won't display offline."
+      "Today's Google doodle, visible only with an active internet connexion, that should be different from the previous one. This will not work on Qtconsole.",
+      "Notebook saved with this kind of image will be lighter and always reflect the current version of the source, but the image won't display offline."
      ]
     },
     {