docs: Add Our Mission Page To Docs

[stackaccount1]

Description

Add our mission page, with summarized mission from the handbook and site.

Motivation and Context

One has to scroll down far to get to the values and principles section on main site. When people are reading the docs, and zkEVM page they should be aware of the strong ethos and mission of Matter Labs and zkSync.

How Has This Been Tested?

local on my computer

Screenshots (if appropriate):

Types of changes

• [ NA] Bug fix (non-breaking change which fixes an issue)
• [x ] New feature (non-breaking change which adds functionality)
• [NA ] Breaking change (fix or feature that would cause existing functionality to change)

Checklist:

• [X ] My code follows the code style of this project.
• [ NA] My change requires a change to the documentation.
• [ NA] I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• [ NA] I have added tests to cover my changes.
• [ NA] All new and existing tests passed.