Add diagrams docs title

docs/diagrams.rst

@@ -1,3 +1,5 @@
+Diagrams
+--------
 
 .. drawio-figure:: ./SpringDamperFTG.drawio
    :format: svg
@@ -6,7 +8,6 @@
 
    Formalism Transformation Graph for the tuning workflow of a spring-mass-damper.
 
-
 .. drawio-figure:: ./SpringDamperPM.drawio
    :format: svg
    :page-index: 1