doxygen: Illegal command n as part of a title section

[himajin100000]

self-reminder

* DocTitle
https://github.com/doxygen/doxygen/blob/208c689e4c13cc065045a6f6b1ff685eda5a3cd6/src/docparser.cpp#L4596
https://github.com/doxygen/doxygen/blob/208c689e4c13cc065045a6f6b1ff685eda5a3cd6/src/docparser.cpp#L4539
https://github.com/doxygen/doxygen/blob/208c689e4c13cc065045a6f6b1ff685eda5a3cd6/src/docparser.cpp#L4547
https://github.com/doxygen/doxygen/blob/208c689e4c13cc065045a6f6b1ff685eda5a3cd6/src/docparser.cpp#L1387

* DocPara
https://github.com/doxygen/doxygen/blob/208c689e4c13cc065045a6f6b1ff685eda5a3cd6/src/docparser.cpp#L4601
https://github.com/doxygen/doxygen/blob/208c689e4c13cc065045a6f6b1ff685eda5a3cd6/src/docparser.cpp#L6593
https://github.com/doxygen/doxygen/blob/208c689e4c13cc065045a6f6b1ff685eda5a3cd6/src/docparser.cpp#L6749
https://github.com/doxygen/doxygen/blob/208c689e4c13cc065045a6f6b1ff685eda5a3cd6/src/docparser.cpp#L6787
https://github.com/doxygen/doxygen/blob/208c689e4c13cc065045a6f6b1ff685eda5a3cd6/src/docparser.cpp#L5489
https://github.com/doxygen/doxygen/blob/208c689e4c13cc065045a6f6b1ff685eda5a3cd6/src/docparser.cpp#L5816