Update README.md for COS notebooks, added new line in table for new ExceptionReport notebook

[annapayne]

This notebook checklist has been made available to us by the Notebooks For All team.
Its purpose is to serve as a guide for both the notebook author and the technical reviewer highlighting critical aspects to consider when striving to develop an accessible and effective notebook.

The First Cell

• The title of the notebook in a first-level heading (eg. <h1> or # in markdown).
• A brief description of the notebook.
• A table of contents in an ordered list (1., 2., etc. in Markdown).
• The author(s) and affiliation(s) (if relevant).
• The date first published.
• The date last edited (if relevant).
• A link to the notebook's source(s) (if relevant).

The Rest of the Cells

• There is only one H1 (# in Markdown) used in the notebook.
• The notebook uses other heading tags in order (meaning it does not skip numbers).

Text

• All link text is descriptive. It tells users where they will be taken if they open the link.
• All acronyms are defined at least the first time they are used.
• Field-specific/specialized terms are used when needed, but not excessively.

Code

• Code sections are introduced and explained before they appear in the notebook. This can be fulfilled with a heading in a prior Markdown cell, a sentence preceding it, or a code comment in the code section.
• Code has explanatory comments (if relevant). This is most important for long sections of code.
• If the author has control over the syntax highlighting theme in the notebook, that theme has enough color contrast to be legible.
• Code and code explanations focus on one task at a time. Unless comparison is the point of the notebook, only one method for completing the task is described at a time.

Images

• All images (jpg, png, svgs) have an image description. This could be

  • Alt text (an alt property)
  • Empty alt text for decorative images/images meant to be skipped (an alt attribute with no value)
  • Captions
  • If no other options will work, the image is decribed in surrounding paragraphs.

• Any text present in images exists in a text form outside of the image (this can be alt text, captions, or surrounding text.)

Visualizations

• All visualizations have an image description. Review the previous section, Images, for more information on how to add it.

• Visualization descriptions include

  • The type of visualization (like bar chart, scatter plot, etc.)
  • Title
  • Axis labels and range
  • Key or legend
  • An explanation of the visualization's significance to the notebook (like the trend, an outlier in the data, what the author learned from it, etc.)

• All visualizations and their parts have enough color contrast (color contrast checker) to be legible. Remember that transparent colors have lower contrast than their opaque versions.

• All visualizations convey information with more visual cues than color coding. Use text labels, patterns, or icons alongside color to achieve this.

• All visualizations have an additional way for notebook readers to access the information. Linking to the original data, including a table of the data in the same notebook, or sonifying the plot are all options.