feat(Search): add "placeholder" & documentation

[rohanrav]

Fixes #3806.

[welcome]

💖 Thanks for opening this pull request! 💖

Here is a list of things that will help get it across the finish line:

• Run yarn lint locally to catch formatting errors. This will fix some errors automatically, commit and push any changes.
• Run yarn test locally to catch errors. This ensures all components still behave as they should.
• Run yarn start to run the doc site locally and try a few pages, ensuring everything is in good working order.
• Include tests when adding/changing behavior.

We get a lot of pull requests on this repo, so please be patient and we will get back to you as soon as we can.

[codecov-commenter]

Codecov Report

Merging #4282 (6cca9a4) into master (8d4558a) will not change coverage.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master    #4282   +/-   ##
=======================================
  Coverage   99.75%   99.75%           
=======================================
  Files         180      180           
  Lines        3241     3241           
=======================================
  Hits         3233     3233           
  Misses          8        8           

Impacted Files	Coverage Δ
src/modules/Search/Search.js	99.55% <100.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 8d4558a...6cca9a4. Read the comment docs.

[rohanrav]

Here is the issue this PR addresses: #3806

[layershifter]

@rohanrav great job, I also added a small unit test 🐱

[welcome]

Congrats on merging your first pull request! 🎉🎉🎉

[noinkling]

Hmm, this change causes the search's <input> element to have a superfluous (no value) placeholder attribute when it isn't provided. I would rather avoid that.

I think it might be because of assigning it an empty string in defaultProps? That doesn't seem necessary to me anyway.

[layershifter]

Hmm, this change causes the search's <input> element to have a superfluous (no value) placeholder attribute when it isn't provided. I would rather avoid that.

I think it might be because of assigning it an empty string in defaultProps? That doesn't seem necessary to me anyway.

@noinkling good call, yeah it should be removed from defaultProps. I will make a PR.

[layershifter]

@noinkling #4327