make xmldocs failed with error after 4.17 merge period

[Masanari Iida]

After merge following patch during 4.17 merger period,
make xmldocs start to fail with error.

 [bdecb33af34f79cbfbb656661210f77c8b8b5b5f]
usb: typec: API for controlling USB Type-C Multiplexers

Error messages.
reST markup error:
/home/iida/Repo/linux-2.6/Documentation/driver-api/usb/typec.rst:215:
(SEVERE/4) Unexpected section title or transition.

------------------------
Documentation/Makefile:93: recipe for target 'xmldocs' failed
make[1]: *** [xmldocs] Error 1
Makefile:1527: recipe for target 'xmldocs' failed
make: *** [xmldocs] Error 2

$

An ascii graphic in typec.rst cause the error.

Masanari Iida