This should hopefully make it easier to quickly identify failing tests
within the CircleCI interface since CircleCI will be able to
programmatically consume the test results.
While this file is actually ignored by a `.gitignore` which lives inside the
`docs` directory (as is consistent with the various docs repositories or
sub-trees), prettier is being told to ignore files in the top-level
`.gitignore` and only supports a single `--ignore-path` file.
This will allow it to skip trying to format this `.json` file.
