Add mermaid to sphinx requirements.

Jelmerdw · Jelmerdw · commit a30a0acf810a · 2025-09-25T15:14:12.000+02:00
Signed-off-by: Jelmer de Wolde &lt;jelmer.de.wolde@alliander.com&gt;
diff --git a/docs/requirements.txt b/docs/requirements.txt
@@ -6,4 +6,5 @@ sphinx>=6.0
 myst-parser
 sphinx_copybutton
 sphinx_rtd_theme
-sphinxcontrib-video
+sphinxcontrib-video
+sphinxcontrib-mermaid
