Remove Page, Retitle Page

[niisita]

Introduction page can be removed and merged into Development, since it doesn't have too much content and no clear CTA.
Merging will help streamline and reduce visual clutter, to help minimize being overwhelmed

Desired outcome:

1. https://eliza.how/development page be relabeled as Overview
2. Remove Introduction

Desired future state:
Getting Started has two pages under

1. Overview
2. Quickstart