chore: Port over mission statement and gtag (#34262)

- [x] I have read [freeCodeCamp's contribution guidelines](https://github.com/freeCodeCamp/freeCodeCamp/blob/master/CONTRIBUTING.md).
- [x] My pull request has a descriptive title (not a vague title like `Update index.md`)
- [x] My pull request targets the `master` branch of freeCodeCamp.


Closes #18184

client/src/analytics/gtag.js

@@ -0,0 +1,29 @@
+const isBrowser = typeof window !== 'undefined';
+
+if (isBrowser) {
+  window.dataLayer = window.dataLayer || [];
+}
+
+function gtag() {
+  if (isBrowser) {
+    window.dataLayer.push(arguments);
+  }
+}
+gtag('js', new Date());
+gtag('config', 'AW-795617839');
+
+export function gtagReportConversion(url) {
+  var callback = function() {
+    if (typeof url !== 'undefined' && isBrowser) {
+      window.location = url;
+    }
+  };
+  if (isBrowser) {
+    gtag('event', 'conversion', {
+      /* eslint-disable camelcase */
+      send_to: 'AW-795617839/AmfiCKHHs4gBEK_UsPsC',
+      event_callback: callback
+    });
+  }
+  return false;
+}

client/src/components/Header/components/Login.js

@@ -6,6 +6,8 @@ import { Button } from '@freecodecamp/react-bootstrap';
 import { hardGoTo } from '../../../redux';
 import { apiLocation } from '../../../../config/env.json';
 
+import { gtagReportConversion } from '../../../analytics/gtag';
+
 import './login.css';
 
 const mapStateToProps = () => ({});
@@ -15,6 +17,7 @@ const mapDispatchToProps = dispatch => ({
 
 const createOnClick = navigate => e => {
   e.preventDefault();
+  gtagReportConversion();
   return navigate(`${apiLocation}/signin`);
 };
 

client/src/head/index.js

@@ -2,9 +2,10 @@ import favicons from './favicons';
 import meta from './meta';
 import mathjax from './mathjax';
 import sassjs from './sassjs';
+import scripts from './scripts';
 
 const metaAndStyleSheets = meta
-  .concat(favicons, mathjax, sassjs)
+  .concat(favicons, mathjax, sassjs, scripts)
   .map((element, i) => ({
     ...element,
     key: `meta-stylesheet-${i}`,

client/src/head/scripts.js

@@ -0,0 +1,10 @@
+import React from 'react';
+
+const scripts = [
+  <script
+    async=''
+    src='https://www.googletagmanager.com/gtag/js?id=AW-795617839'
+  />
+];
+
+export default scripts;

client/src/pages/index.css

@@ -52,7 +52,9 @@
   margin-left: 20px;
   margin-right: 20px;
 }
-
+.underlined-link {
+  text-decoration: underline;
+}
 @media (min-width: 991px) and (max-width: 1199px) {
   .testimonial-copy {
     height: 150px;

client/src/pages/index.js

@@ -88,7 +88,7 @@ const IndexPage = () => (
       <Spacer />
       <h2>As featured in:</h2>
       <Image
-        alt="companies featuring freeCodeCamp"
+        alt='companies featuring freeCodeCamp'
         className='img-center'
         responsive={true}
         src='https://s3.amazonaws.com/freecodecamp/as-seen-on.png'
@@ -212,7 +212,32 @@ const IndexPage = () => (
           <h2 className='black-text'>D3.js</h2>
         </Col>
       </Row>
+      <hr />
       <Spacer />
+      <h3>
+        freeCodeCamp is a donor-supported tax-exempt 501(c)(3) nonprofit
+        organization (United States Federal Tax Identification Number:
+        82-0779546)
+      </h3>
+      <p className='large-p'>
+        Our mission: to help people learn to code for free. We accomplish this
+        by creating thousands of videos, articles, and interactive coding
+        lessons - all freely available to the public. We also have thousands of
+        freeCodeCamp study groups around the world.
+      </p>
+      <p className='large-p'>
+        Donations to freeCodeCamp go toward our education initiatives, and help
+        pay for servers, services, and staff. You can{' '}
+        <a
+          className='large-p underlined-link'
+          href='https://donate.freecodecamp.org/'
+          rel='noopener noreferrer'
+          target='_blank'
+          >
+          make a tax-deductible donation here
+        </a>
+      </p>
+      .<Spacer />
       <BigCallToAction />
       <Spacer />
       <Spacer />