Add a note about what sort of ligatures disable_ligatures affects

kitty/config_data.py

@@ -304,6 +304,9 @@ or by defining shortcuts for it in kitty.conf, for example::
     map alt+2 disable_ligatures_in all never
     map alt+3 disable_ligatures_in tab cursor
 
+Note that this refers to programming ligatures, typically implemented using the
+:code:`calt` OpenType feature. For disabling general ligatures, use the
+:opt:`font_features` setting.
 '''))
 
 o('font_features', 'none', long_text=_('''