Added aria label to element

[kalaspuffar]

Fixes #98

Added aria label to the element so it is in the same shadow DOM and read by screen readers.

I wondered why I wasn't able to get the screen reader to read the label of my input-textarea and it seems to be because of encapsulation between components.

Tested on Chrome with NVDA screen reader.

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[kalaspuffar]

I signed it!

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