add text to social media links in footer

[jaredbain]

Adds accessibility text to social media links in footer

Fixes #327

Checklist

• My code follows the existing style, code structure, and naming taxonomy
• I have performed a self-review of my own code and have no open issues
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings or syntax errors
• I have verified Draft on actual mobile devices, especially Safari-based

[chriskuang4]

thank you!