Update explanation regarding Raw cells (#632)

Author: 1kastner

doc/images/raw_cells.png

@@ -15,17 +15,46 @@
    "source": [
     "# Raw Cells\n",
     "\n",
-    "The \"Raw NBConvert\" cell type can be used to render different code formats into HTML or LaTeX by Sphinx.  This information is stored in the notebook metadata and converted appropriately.\n",
+    "Any Jupyter Notebook consists of cells of three different types:\n",
+    "[Code cells](./code-cells.ipynb),\n",
+    "[Markdown cells](./markdown-cells.ipynb)\n",
+    ", and/or Raw cells.\n",
+    "While most Jupyter Notebook users are very familiar with Code cells and Markdown cells in Jupyter Notebooks, Raw cells are less frequently used.\n",
+    "For Jupyter Notebook, they are introduced\n",
+    "[here](https://jupyter-notebook.readthedocs.io/en/stable/notebook.html?highlight=raw#raw-cells)\n",
+    "and for JupyterLab\n",
+    "[here](https://jupyterlab.readthedocs.io/en/stable/extension/notebook.html?highlight=raw#model).\n",
+    "The Raw cells are also sometimes referred to as Raw NBConvert cells in the context of\n",
+    "[nbconvert](https://nbconvert.readthedocs.io/en/latest/architecture.html?highlight=raw#a-detailed-pipeline-exploration).\n",
+    "The Raw cell type can be used to render different code formats into HTML or LaTeX by Sphinx.\n",
+    "This information is stored in the notebook metadata and converted appropriately.\n",
     "\n",
     "## Usage\n",
     "\n",
-    "To select a desired format from within Jupyter, select the cell containing your special code and choose options from the following dropdown menus:  \n",
+    "Raw cells are created differently depending on the user interface.\n",
     "\n",
-    "1. Select \"Raw NBConvert\"\n",
-    "2. Switch the Cell Toolbar to \"Raw Cell Format\"\n",
-    "3. Chose the appropriate \"Raw NBConvert Format\" within the cell\n",
+    "### Jupyter Notebook\n",
     "\n",
-    "![Steps for converting cells to Raw formats in Jupyter](images/raw_cells.png)\n",
+    "To select a desired format from within Jupyter Notebook, select the cell containing your special code and choose options from the following dropdown menus:\n",
+    "\n",
+    "1. Select \"Raw NBConvert\" in the Menu Toolbar (just below the two menus \"Widgets\" and \"Help\").\n",
+    "2. Click on the \"Raw NBConvert Format\" dropdown menu within the cell and select \"reST\".\n",
+    "\n",
+    "![Steps for converting cells to Raw formats in Jupyter Notebook](images/raw_cells_jupyter_notebook.png)\n",
+    "<!-- this comment makes pandoc create an in-line image -->\n",
+    "\n",
+    "### JupyterLab\n",
+    "\n",
+    "To select a desired format from within JupyterLab, first activate the right sidebar by clicking on View in the Menu Toolbar.\n",
+    "Then you ensure that in front of Show Right Sidebar there is a tick.\n",
+    "Once the Right Sidebar is shown, you are ready to go.\n",
+    "\n",
+    "Now you select the cell containing your special code and choose options from the following dropdown menus:\n",
+    "\n",
+    "1. Select \"Raw\" in the Notebook Toolbar (just next to the symbols that run cells or reload the kernel).\n",
+    "2. Click on \"Raw NBConvert Format\" in the Right Sidebar and select \"reStructured Text\".\n",
+    "\n",
+    "![Steps for converting cells to Raw formats in JupyterLab](images/raw_cells_jupyterlab.png)\n",
     "<!-- this comment makes pandoc create an in-line image -->"
    ]
   },
@@ -176,5 +205,5 @@
   }
  },
  "nbformat": 4,
- "nbformat_minor": 1
+ "nbformat_minor": 4
 }