faq: turd files, typo and clean example

other/faq.rst

@@ -41,7 +41,7 @@ automatically become an ascii file.
 heudiconv/bids: UnicodeDecodeError
 ------------------------
 
-When running Heudiconv, Apple users sometimes notice an error similar to this:
+When running Heudiconv, macOS users sometimes notice an error similar to this:
 
 .. code-block:: python
 
@@ -63,3 +63,6 @@ Usually this indicates that Heudiconv tried to load json files that are in fact
 avoid their creation and you will have to clean them manually. Other
 workarounds are setting your BIDS folder read-only before loading them in Finder or
 avoiding Finder altogether.
+
+To clean them try running **either**: `dot_clean -m bids_folder` on your Mac or
+`find bids_folder -name '._*' -delete` on a Linux/macOS.