aXe audit: Form elements must have labels

[paulathevalley]

Running the aXe: the accesibility engine chrome extension yields a critical violation: Form elements must have labels.

The target in question is <textarea ref="textarea" ... https://github.com/JedWatson/react-codemirror/blob/master/src/Codemirror.js#L85

Summary: Fix any of the following:

• aria-label attribute does not exist or is empty
• aria-labelledby attribute does not exist, references elements that do not exist or references elements that are empty or not visible
• Form element does not have an implicit (wrapped)
• Form element does not have an explicit
• Element has no title attribute or the title attribute is empty