user-guide: add interventions section

* Closes #626
* Attempt to document the most common operator interventions.
* Add the sphinx-design library to the docs environment for tabbed
  selectors.

Author: oliver-sanders

setup.cfg

@@ -52,6 +52,7 @@ install_requires =
     hieroglyph>=2.1.0
     setuptools>=50
     sphinx>=7.1
+    sphinx-design>=0.5.0
     sphinx_rtd_theme>=1.0.0
     sphinxcontrib-svg2pdfconverter
     sphinxcontrib-spelling

src/conf.py

@@ -43,6 +43,7 @@
     # sphinx user community extensions
     'hieroglyph',
     'sphinx_rtd_theme',
+    'sphinx_design',
     # custom project extensions (located in ext/)
     'autodoc_traits',  # autodoc uiserver traitlets
     'database_diagram',

src/user-guide/index.rst

@@ -9,6 +9,7 @@ User Guide
 
    introduction
    examples/index
+   interventions/index
    writing-workflows/index
    installing-workflows
    running-workflows/index