Document shebang comment behaviour (#3787)

docs/the_black_code_style/current_style.md

@@ -254,11 +254,12 @@ required due to an inner function starting immediately after.
 
 _Black_ does not format comment contents, but it enforces two spaces between code and a
 comment on the same line, and a space before the comment text begins. Some types of
-comments that require specific spacing rules are respected: doc comments (`#: comment`),
-section comments with long runs of hashes, and Spyder cells. Non-breaking spaces after
-hashes are also preserved. Comments may sometimes be moved because of formatting
-changes, which can break tools that assign special meaning to them. See
-[AST before and after formatting](#ast-before-and-after-formatting) for more discussion.
+comments that require specific spacing rules are respected: shebangs (`#! comment`), doc
+comments (`#: comment`), section comments with long runs of hashes, and Spyder cells.
+Non-breaking spaces after hashes are also preserved. Comments may sometimes be moved
+because of formatting changes, which can break tools that assign special meaning to
+them. See [AST before and after formatting](#ast-before-and-after-formatting) for more
+discussion.
 
 ### Trailing commas