PXC-4414 Apply new colour scheme, add a link and new icon to PXC (8.0) (

#149)

* PXC-4414 Apply new colour scheme, add a link and new icon to PXC (8.0)
	new file:   _resource/overrides/partials/header.html
	new file:   docs/assets/mysql-fav.svg
	new file:   docs/assets/mysql-mark.svg
	modified:   docs/css/design.css
	new file:   docs/css/landing.css
	new file:   docs/css/mysql.css
	modified:   mkdocs-base.yml

* Update header.html

_resource/overrides/partials/header.html

@@ -0,0 +1,113 @@
+<!-- Determine classes -->
+{% set class = "md-header" %}
+{% if "navigation.tabs.sticky" in features %}
+  {% set class = class ~ " md-header--shadow md-header--lifted" %}
+{% elif "navigation.tabs" not in features %}
+  {% set class = class ~ " md-header--shadow" %}
+{% endif %}
+
+<!-- Header -->
+<header class="{{ class }}" data-md-component="header">
+
+  <!-- Super Nav -->
+  <div class="superNav">
+    <div class="md-header__inner md-grid">
+      <a href="https://docs.percona.com/percona-for-mysql/" title="Percona Documentation home page">
+        <svg width="24" height="24" xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24">
+          <mask id="a" style="mask-type:alpha" maskUnits="userSpaceOnUse" x="0" y="0" width="24" height="24">
+            <path d="M0 0h24v24H0z"/>
+          </mask>
+          <g mask="url(#a)">
+            <path d="m7.825 13 5.6 5.6L12 20l-8-8 8-8 1.425 1.4-5.6 5.6H20v2H7.825Z"/>
+          </g>
+        </svg>
+        <span>Percona Documentation</span>
+      </a>
+    </div>
+  </div>
+
+  <nav
+    class="md-header__inner md-grid"
+    aria-label="{{ lang.t('header') }}"
+  >
+
+    <!-- Link to home -->
+    <a
+      href="{{ config.extra.homepage | d(nav.homepage.url, true) | url }}"
+      title="{{ config.site_name | e }}"
+      class="md-header__button md-logo"
+      aria-label="{{ config.site_name }}"
+      data-md-component="logo"
+    >
+      {% include "partials/logo.html" %}
+    </a>
+
+    <!-- Button to open drawer -->
+    <label class="md-header__button md-icon" for="__drawer">
+      {% set icon = config.theme.icon.menu or "material/menu" %}
+      {% include ".icons/" ~ icon ~ ".svg" %}
+    </label>
+
+    <!-- Header title -->
+    <div class="md-header__title">
+      <div class="md-header__ellipsis">
+        <a href="{{ config.extra.homepage | d(nav.homepage.url, true) | url }}" class="md-header__topic">
+          <span class="md-ellipsis">
+            {{ config.site_name }}
+          </span>
+        </a>
+        <div class="md-header__topic" data-md-component="header-topic">
+          <span class="md-ellipsis">
+            {% if page.meta and page.meta.title %}
+              {{ page.meta.title }}
+            {% else %}
+              {{ page.title }}
+            {% endif %}
+          </span>
+        </div>
+      </div>
+    </div>
+
+    <!-- Color palette toggle -->
+    {% if config.theme.palette %}
+      {% if not config.theme.palette is mapping %}
+        {% include "partials/palette.html" %}
+      {% endif %}
+    {% endif %}
+
+    <!-- User preference: color palette -->
+    {% if not config.theme.palette is mapping %}
+      {% include "partials/javascripts/palette.html" %}
+    {% endif %}
+
+    <!-- Site language selector -->
+    {% if config.extra.alternate %}
+      {% include "partials/alternate.html" %}
+    {% endif %}
+
+    <!-- Button to open search modal -->
+    {% if "material/search" in config.plugins %}
+      <label class="md-header__button md-icon" for="__search">
+        {% set icon = config.theme.icon.search or "material/magnify" %}
+        {% include ".icons/" ~ icon ~ ".svg" %}
+      </label>
+
+      <!-- Search interface -->
+      {% include "partials/search.html" %}
+    {% endif %}
+
+    <!-- Repository information -->
+    {% if config.repo_url %}
+      <div class="md-header__source">
+        {% include "partials/source.html" %}
+      </div>
+    {% endif %}
+  </nav>
+
+  <!-- Navigation tabs (sticky) -->
+  {% if "navigation.tabs.sticky" in features %}
+    {% if "navigation.tabs" in features %}
+      {% include "partials/tabs.html" %}
+    {% endif %}
+  {% endif %}
+</header>