Returns the meaning of the field.

[taoharry]

Hello, I have a suggestion. I wonder if you can provide a copy of the field meaning of demo (https://certstream.calidog.io/example.json) in the readme? Although you can guess the meaning of most fields by looking at words, it always feels that the description is not very accurate after translation. If there is a description of each field, it will feel better to read. Thank you.