docs: Unfold INPUT items into multiple lines
diff --git a/doxygen.cfg.in b/doxygen.cfg.in
index b92f9d2..e734df5 100644
--- a/doxygen.cfg.in
+++ b/doxygen.cfg.in
@@ -819,7 +819,9 @@
# spaces. See also FILE_PATTERNS and EXTENSION_MAPPING
# Note: If this tag is empty the current directory is searched.
-INPUT = include/@PACKAGE@ README.md
+INPUT = \
+ include/@PACKAGE@ \
+ README.md
# This tag can be used to specify the character encoding of the source files
# that doxygen parses. Internally doxygen uses the UTF-8 encoding. Doxygen uses
