Add speakeasy sponsorship (encode#3305)

Author: lovelydinosaur

docs/img/speakeasy.png

@@ -0,0 +1,54 @@
+{% import "partials/nav-item.html" as item with context %}
+
+<!-- Determine class according to configuration -->
+ {% set class = "md-nav md-nav--primary" %}
+ {% if "navigation.tabs" in features %}
+   {% set class = class ~ " md-nav--lifted" %}
+ {% endif %}
+ {% if "toc.integrate" in features %}
+   {% set class = class ~ " md-nav--integrated" %}
+ {% endif %}
+
+ <!-- Main navigation -->
+ <nav
+   class="{{ class }}"
+   aria-label="{{ lang.t('nav.title') }}"
+   data-md-level="0"
+ >
+
+   <!-- Site title -->
+   <label class="md-nav__title" for="__drawer">
+     <a
+       href="{{ config.extra.homepage | d(nav.homepage.url, true) | url }}"
+       title="{{ config.site_name | e }}"
+       class="md-nav__button md-logo"
+       aria-label="{{ config.site_name }}"
+       data-md-component="logo"
+     >
+       {% include "partials/logo.html" %}
+     </a>
+     {{ config.site_name }}
+   </label>
+
+   <!-- Repository information -->
+   {% if config.repo_url %}
+     <div class="md-nav__source">
+       {% include "partials/source.html" %}
+     </div>
+   {% endif %}
+
+   <!-- Navigation list -->
+   <ul class="md-nav__list" data-md-scrollfix>
+     {% for nav_item in nav %}
+       {% set path = "__nav_" ~ loop.index %}
+       {{ item.render(nav_item, path, 1) }}
+     {% endfor %}
+   </ul>
+
+   <ul class="md-nav__list" data-md-scrollfix style="padding-top: 15px; padding-left: 10px">
+     <div>
+       <a href="https://speakeasy.com"><img src="/img/speakeasy.png" width=150px style=></img></a>
+     </div>
+   </ul>
+ </nav>
+ 

docs/overrides/partials/nav.html

@@ -4,6 +4,7 @@ site_url: https://www.python-httpx.org/
 
 theme:
     name: 'material'
+    custom_dir: 'docs/overrides'
     palette:
       - scheme: 'default'
         media: '(prefers-color-scheme: light)'