testSetTextStateManager unit test documentation is incorrect

Test function testSetTextStateManager documentation is incorrect:
qtsaferenderer/tests/auto/saferenderer/tst_qsaferenderer.cpp from line 4253 onwards.
It refers to already documented function testTextLayoutReadingFromFile.

This causes documentation error: qtsaferenderer/tests/auto/saferenderer/tst_qsaferenderer.cpp:4252: error: HTML file already exists; overwriting
as '\page testTextLayoutReadingFromFile.html' is defined twice.