Move RTD ads to the sidebar

Author: jsiirola

doc/OnlineDocs/_templates/ethicalads.html

@@ -0,0 +1 @@
+<div id="ethical-ad-placement"></div>

doc/OnlineDocs/conf.py

@@ -183,6 +183,15 @@
 #
 html_theme_options = {'navigation_depth': 6, 'titles_only': True}
 
+html_sidebars = {
+    "**": [
+        "localtoc.html",
+        "relations.html",
+        "ethicalads.html",  # Put the ad below the navigation and previous/next
+        "sourcelink.html",
+        "searchbox.html",
+    ]
+}
 # Add any paths that contain custom static files (such as style sheets) here,
 # relative to this directory. They are copied after the builtin static files,
 # so a file named "default.css" will overwrite the builtin "default.css".