Fix accessibility bug: fully comment out disabled main menu entry

[[menu.main]] was left active while its name/url/weight fields were
commented out, so Hugo built one real menu entry with no name or URL.
The header template rendered it as an empty <a href="">, which screen
readers announce using the resolved href (the current page's own URL)
since there's no text or aria-label -- e.g. reading "freebie" on the
freebie page.

hugo.toml

@@ -14,7 +14,7 @@ disableKinds = ["taxonomy", "term"]
   author = "Will Estes"
   eec_base_url = "https://eec.reground.org"
 
-[[menu.main]]
+# [[menu.main]]
 #   name = "Courses"
 #   url = "/courses/"
 #   weight = 10