add wy 2021 river conditions

[cnell-usgs]

Changes made:

adding the 2021 water year river conditions to the events carousel and making naming more intuitive

Testing:

Before making this pull request, I:

• Cleaned the code the way Vue likes it - run 'npm run lint --fix'
• Made sure all tests run
• Ran WAVE plugin 508 compliance tool

I can confirm this has been checked on:

• Chrome
• Safari
• Edge
• Firefox
• Samsung Internet
• Internet Explorer 11 (not supported, but still needs at least a working user redirect page)

[cnell-usgs]

Merging this. Minimal change to rename "hurricanes" to "Events" to include river conditions.

FYI to @hcorson-dosch: to add elements you just add the information to the csv committed to the repo. The group column defines which carousel it gets placed in, and img is the thumbnail file. This reads in files from s3 with the root path https://labs.waterdata.usgs.gov/visualizations/thumbnails/. The steps to push thumbnail files to s3 has not been added formally into this pipeline (#22)