Fix social media logo visibility by setting og:image to black logo

Co-authored-by: honzajavorek <283441+honzajavorek@users.noreply.github.com>

Author: Copilot

docs/_templates/page.html

@@ -9,3 +9,10 @@
     {%- endif -%}
   </title>
 {%- endblock -%}
+
+{%- block extrahead %}
+  {{ super() }}
+  <meta property="og:image" content="{{ pathto('_static/images/org.svg', 1) }}" />
+  <meta property="og:image:type" content="image/svg+xml" />
+  <meta property="og:image:alt" content="Pyvec logo" />
+{%- endblock -%}