Here are the options removed and the replacements.

Option prior to 2.0.0	Option in 2.0.0
[MQTTSubscribeDriver] or [MQTTSubscribeService]   topic = topic-name	[[topics]]   [[[topic-name]]] For additional information see.
[MQTTSubscribeDriver] or [MQTTSubscribeService]   overlap =	[[topics]]   adjust_start_time = and/or adjust_end_time = For additional information see.
[[archive_field_cache]]   [[[fields]]]     [[[[field-name]]]]       expires_after =	[[topics]]   [[[topic-name]]]     [[[[field-name]]]]       expires_after = For additional information see.
[[message_callback]]   full_topic_fieldname = True	[[topics]]   [[[topic-name]]]     [[[[field-name]]]] With the field definition under the topic, name clashes across topics cannoy happen and therefore this option is no longer needed.
[[message_callback]]   contains_total = field-name	[[topics]]   [[[topic-name]]]     [[[[field-name]]]]       contains_total = True For additional information see.
[[message_callback]]     [[[label_map]]]    field-name = WeeWX-name	[[topics]]   [[[topic-name]]]     [[[[field-name]]]]       name = WeeWX-name For additional information see.
[[message_callback]]   [[[fields]]]     [[[[field-name]]]]	[[topics]]   [[[topic-name]]]     [[[[field-name]]]] For additional information see.
[[topics]]   use_topic_as_fieldname = True	In 2.0.0 this option is no longer needed. MQTTSubscribe will use the topic as the fieldname if there are no [[[[field-name]]]] sections and at least one field configuration option is found.