[ticket/11663] Make generate_text_for_storage return the errors.

generate_text_for_storage does not return anything, all returned values are outputted using the parameters so this uses the returned value with the same idea as many C language functions where the returned value is if all went well or not and if it didn't what went wrong.

PHPBB3-11663
[ticket/11663] Add the doc block about the return value.

generate_text_for_storage does not return anything, all returned values are outputted using the parameters so this uses the returned value with the same idea as many C language functions where the returned value is if all went well or not and if it didn't what went wrong.

PHPBB3-11663
[ticket/11663] Add the doc block about the parameters.

PHPBB3-11663
Merge remote-tracking branch 'brunoais/ticket/11663' into develop

* brunoais/ticket/11663:
  [ticket/11663] Add the doc block about the parameters.
  [ticket/11663] Add the doc block about the return value.
  [ticket/11663] Make generate_text_for_storage return the errors.