feat(Avatar): adding alt property

[mnajdova]

Avatar

Adding alt property to the Avatar component, for propagation to the Image component.

Proposed API:

alt

<Avatar src="path/to/image.jpg" alt="Profile picture of Matt" />

Result:

<div class="ui-avatar f g h">
  <img src="path/to/image.jpg" alt="Profile picture of Matt" class="ui-image f g i q i" />
</div>

[codecov]

Codecov Report

Merging #124 into master will not change coverage.
The diff coverage is 66.66%.

@@           Coverage Diff           @@
##           master     #124   +/-   ##
=======================================
  Coverage   69.94%   69.94%           
=======================================
  Files          74       74           
  Lines        1198     1198           
  Branches      227      227           
=======================================
  Hits          838      838           
  Misses        355      355           
  Partials        5        5

Impacted Files	Coverage Δ
src/components/Avatar/Avatar.tsx	76% <66.66%> (ø)	⬆️

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[levithomason]

This is a bit odd. Some components won't have shorthand examples, such as this Avatar. Unless the avatar were used in another component like this:

<SomeComponent
  avatar={{ src: '//placehold.it/100', alt: 'A placeholder image' }}
/>

It seems we should not require certain components like Avatar to show shorthand. Let's plan on fixing that. No need to block this PR though.

[levithomason]

This is a very helpful description. Grammar suggestion:

An Avatar can specify alternative text for the image.

[levithomason]

This is actually a nice description as well and has good grammar. It could also be used in the docs if you prefer it over my other suggestion.

[levithomason]

Please update alt description grammar using one of the suggestions.