Fix some typeos in index.

index.ipynb

@@ -8,9 +8,9 @@
     "# The FEniCSx tutorial\n",
     "Author: Jørgen S. Dokken\n",
     "\n",
-    "This webpage gives a concise overview of the functionality of [DOLFINx](https://github.com/FEniCS/dolfinx/), including a gentle introduction to the finite element method. This webpage is an adaptation of the FEniCS tutorial {cite}`FenicsTutorial`.\n",
+    "These webpages give a concise overview of the functionality of [DOLFINx](https://github.com/FEniCS/dolfinx/), including a gentle introduction to the finite element method. This webpage is an adaptation of the FEniCS tutorial {cite}`FenicsTutorial`.\n",
     "\n",
-    "DOLFINx can be used as either a C++ or Python software, but this tutorial will focus on Python programming, as it is the simplest and most effective approach for beginners. After having gone through this tutorial, the reader should familiarize themselves with the DOLFINx [documentation](https://docs.fenicsproject.org/dolfinx/main/python/), which includes the API and numerous demos.\n",
+    "DOLFINx can be used as either C++ or Python software, but this tutorial will focus on Python programming, as it is the simplest and most effective approach for beginners. After having gone through this tutorial, the reader should familiarize themselves with the DOLFINx [documentation](https://docs.fenicsproject.org/dolfinx/main/python/), which includes the API and numerous demos.\n",
     "\n",
     "Comments and corrections to this webpage should be submitted to the issue tracker by going to the relevant page in the tutorial, then click the ![git](git.png)-symbol in the top right corner and \"open issue\".\n",
     "\n",