[MIRROR] updates bb convert objective text (#2124)

* updates bb convert objective text (#81658)

## About The Pull Request

adds some explainer text to BB conversion.

## Why It's Good For The Game

I've run into several people recently having issues with this - not
knowing who they can convert or what to do if they lose/break their
flash without successfully converting. Adds a little bit of text to
hopefully help.

## Changelog

:cl:
qol: Blood Brother convert objective now explains who you can convert
and what to do if you mess up with your flash.
/:cl:

* updates bb convert objective text

---------

Co-authored-by: NovaBot <[email protected]>
Co-authored-by: Higgin <[email protected]>

code/modules/antagonists/brother/brother.dm

@@ -210,7 +210,7 @@
 
 /datum/objective/convert_brother
 	name = "convert brother"
-	explanation_text = "Convert someone else using your flash."
+	explanation_text = "Convert a brainwashable person using your flash. Any flash will work if you lose or break your starting flash."
 	admin_grantable = FALSE
 	martyr_compatible = TRUE