proper aria handling

[jonespen]

• Update docs
• Add tests for all prop functions

[codecov-io]

Codecov Report

Merging #3 into master will decrease coverage by 3.7%.
The diff coverage is 91.66%.

@@            Coverage Diff             @@
##           master       #3      +/-   ##
==========================================
- Coverage     100%   96.29%   -3.71%     
==========================================
  Files           2        2              
  Lines          24       27       +3     
  Branches        4        5       +1     
==========================================
+ Hits           24       26       +2     
- Misses          0        1       +1

Impacted Files	Coverage Δ
src/index.js	96.15% <91.66%> (-3.85%)	⬇️

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