update config (goldmark.extensions)

adds extra extension but has to disable strikethrough extension
(extra includes strikethrough)

config/_default/markup.toml

@@ -3,6 +3,13 @@
 
 # let us put inline html into the markdown files
 [goldmark]
+  [goldmark.extensions]
+    strikethrough = false
+    [goldmark.extensions.extras]
+      [goldmark.extensions.extras.delete]
+        enable = true
+      [goldmark.extensions.extras.subscript]
+        enable = true
   [goldmark.renderer]
     unsafe = true
 
@@ -18,4 +25,3 @@
   [tableOfContents]
     startLevel = 2
     endLevel = 4
-