Update developer_guide.md

Author: infradom

docs/developer_guide.md

@@ -107,8 +107,7 @@ The meaning of the parameters of a button autorepeat value_function is:
 * descr: the entity description object of the button
 * datadict: the dictionary with all the known entity values
 
-In its current form, the function should return a dictionary containing following items:
-
+In its current form, the function should return a dictionary containing following items: 
 - `action`: the modbus type of write to be executed: currently only MODBUS_WRITE_MULTI is suppored, but the other writes can be easily added later.
 - `register` (optional): if not specified, the register address for the autorepeat button will be used
 - `data`: a list of tuples `[ (entity_key, value,), ....]` that represents the payload of a write_multiple command that starts at the modbus register addres. Instead of the entity_key_name, a register type can also be specified like `REGISTER_U16`. The payload should not contain the button's entity itself, just the data that needs to be added in the write_multiple scenario. In the future, the `data` structure may be modified to allow other types of writes.