docs: conf: extensions: Enable mermaid diagram extension

[johnandersen777]

diff --git a/docs/conf.py b/docs/conf.py
index a31b24ea4..ebc2fa543 100644
--- a/docs/conf.py
+++ b/docs/conf.py
@@ -64,6 +64,7 @@ extensions = [
     "literalinclude_relative",
     "nbsphinx",
     "nbsphinx_link",
+    "sphinxcontrib-mermaid",
 ]

 intersphinx_mapping = {"python": ("https://docs.python.org/3", None)}
diff --git a/requirements-dev.txt b/requirements-dev.txt
index a9faeb6de..227d3598c 100644
--- a/requirements-dev.txt
+++ b/requirements-dev.txt
@@ -21,3 +21,4 @@ matplotlib
 # Needed to run DataFrame test, not required for module
 pandas>=1.0
 lxml>=4.6.3
+sphinxcontrib-mermaid>=0.7.1

[johnandersen777]

Blocked by mgaitan/sphinxcontrib-mermaid#74