Functionality of aria-labelledby and aria-describedby

[rshen91]

Opening this issue in response to https://github.com/elastic/elastic-charts/pull/1472#discussion_r785134078. As mentioned,

NVDA will store something like 88 characters, and I've experienced VoiceOver stop reading in the middle of a long live region announcement.

Using this issue to start a conversation with UX Research team to discuss if this works as intended with testers

[1Copenut]

@rshen91 It appears JAWS has a default line length of 150 characters and NVDA a default of 100 characters:

Maximum Line Length Default = 150 characters. This determines how many characters the Virtual PC cursor treats as one line of text. JAWS Settings

In browse mode, you can set the line length. The default is one-hundred carachters. (sic) Re: More flexible line length in browsing mode

Users can adjust these defaults, but we won't have access to those metrics. If semantic labels are longer than say, 75 characters, I think we could have a general description telling users they may need to advance their buffer once or twice to hear the entire label. "Buffer" is not a great description, it'd need rewritten to use plain language, but that gives us a starting point.