Some image assets are missing

[jcgiuffrida]

The following image assets referenced in cds-navbar.scss are not in this repo:

PNG

• angle-arrow-down.png
• angle-arrow-down-hover.png
• angle-arrow-down-primary.png
• angle-arrow-up-primary.png
• minus.png
• plus.png
• minus-alt.png
• plus-alt.png
• search-alt.png

SVG

• plus.svg
• search-alt.svg

These appear to be FontAwesome icons but some of them, like search-alt, are not current icons in FA 5.