privacytools.io sponsorships (#1451)

* Add sponsorship sections and information

* Correct typographical error

* Minor adjustments

_includes/nav.html

@@ -142,8 +142,8 @@
         </details>
 
         <a href="https://blog.privacytools.io/" class="nav-anchor">Blog </a>
-        <a href="/donate/" class="nav-anchor">
-          Donate <span class="fas fa-heart text-danger fa-fw"></span>
+        <a href="/sponsors/" class="nav-anchor">
+          Sponsors
         </a>
         <span id="nav-switch-theme" class="nav-anchor">
           Theme <span class="nav-theme-icon fas fa-fw"></span>