btrfs-progs: docs: add extra LLM disclosure following kernel guidelines

There are increased LLM assisted bug fixes in the mailing list, and I
have a very strong feeling that most of the new bug fixes from unknown
developers are at least assisted of LLM, and they never properly
disclose the usage of LLM.

I don't know much difference such updated docs will make, but at least
let's try to make them disclose the LLM usage.

Signed-off-by: Qu Wenruo <wqu@suse.com>

Author: adam900710

Documentation/dev/Developer-s-FAQ.rst

@@ -36,6 +36,10 @@ highlight the most frequently used tags and their expected meaning. This only
 briefly mentions the commonly used tags. You're encouraged to read the whole
 document and get familiar with it.
 
+With the recent increased flow of LLM-assisted bug fixes, please also follow the
+kernel documentation at https://docs.kernel.org/process/coding-assistants.html to
+properly disclose LLM usage for every patch.
+
 Signed-off-by:
 ^^^^^^^^^^^^^^