Update Nav

[emaela]

Let's update the navigation to match the new design. There will be 5 tabs: 'home', 'students', 'clients', 'projects', and 'team'.
The 'home' and 'team' buttons can lead to the current home and team pages.
The 'students', 'clients', and 'projects' pages will be new pages.

Specs:

• Update navigation to match new design
• Create new pages for 'students', 'clients', and 'projects'
• Ensure each tab leads to the appropriate page

Notes:

• May have to change gatsby-config.js