Replace the Sitemap With a Search Feature

### Overview

We need to replace the site map with a search feature because the site map is out of date.

### Action Items
- [ ] Add the following sentences to the header in a new paragraph each:
- `The Hack for LA website is growing. We started with a one page website, and we have been steadily adding content and features to accommodate our fully remote brigade.`
- `Our sitemap is currently out of date. Please use the footer or this search instead.`
- [ ] Create and add a search feature below the header to search for any page on the website
- [ ] Remove the site map from the page
- [ ] Create a PR

### Resources/Instructions
- 1.01 Sitemap code: https://github.com/hackforla/website/blob/gh-pages/pages/sitemap.html
- 1.02 Website: https://www.hackforla.org/sitemap/