docs: use MyST fieldlist and substitution

docs/source/conf.py

@@ -20,8 +20,6 @@ from jupyterhub.app import JupyterHub
 project = "JupyterHub"
 author = "Project Jupyter Contributors"
 copyright = f"{datetime.date.today().year}, {author}"
-version = "%i.%i" % jupyterhub.version_info[:2]
-release = jupyterhub.__version__
 
 
 # -- General Sphinx configuration --------------------------------------------
@@ -48,11 +46,21 @@ default_role = "literal"
 # ref: https://myst-parser.readthedocs.io/en/latest/configuration.html
 #
 myst_heading_anchors = 2
+
 myst_enable_extensions = [
+    # available extensions: https://myst-parser.readthedocs.io/en/latest/syntax/optional.html
     "colon_fence",
     "deflist",
+    "fieldlist",
+    "substitution",
 ]
 
+myst_substitutions = {
+    # date example: Dev 07, 2022
+    "date": datetime.date.today().strftime("%b %d, %Y").title(),
+    "version": jupyterhub.__version__,
+}
+
 
 # -- Custom directives to generate documentation -----------------------------
 # ref: https://myst-parser.readthedocs.io/en/latest/syntax/roles-and-directives.html