`allow-long-titles` option incorrectly skipping non-title lines

[zeyi2]

Hi, I'm from clang-tidy. I noticed an issue where allow-long-titles = true incorrectly exempts entire sections from line length checks (D001).

Link to where the issue happened: llvm/llvm-project#173484 (comment)

Reproducer:

• doc8.ini

[doc8]
allow-long-titles = true
max-line-length = 40

• repro.rst

.. title:: clang-tidy - misc-anonymous-namespace-in-header

misc-anonymous-namespace-in-header
==================================

Finds anonymous namespaces in headers.

Anonymous namespaces in headers can lead to One Definition Rule (ODR) violations
because each translation unit including the header will get its own unique version
of the symbols. This increases binary size and can cause confusing link-time errors.

References
----------

This check corresponds to the CERT C++ Coding Standard rule
`DCL59-CPP. Do not define an unnamed namespace in a header file
<https://wiki.sei.cmu.edu/confluence/display/cplusplus/DCL59-CPP.+Do+not+define+an+unnamed+namespace+in+a+header+file>`_.

Corresponding cpplint.py check name: `build/namespaces`.

doc8 gives:

repro.rst:8: D001 Line too long
repro.rst:19: D001 Line too long