Allow framed section titles

[linawolf]

Section titles can be underlined by a series of the same signs or underlined and overlined by those

https://www.sphinx-doc.org/en/master/usage/restructuredtext/basics.html#sections

In the TYPO3 docs we use the a section title framed by equatation marks to mark the main Document title.

the doctrine/rst-parser currently interprets this as a hr followed by a section of the same level as Topic 1 bellow.

========
DocTitle
========

About this document ...

Topic 1
=======
Here we go.

Subtopic 1.1
------------
Here we dive deeper

Subsubtopic 1.1.1
~~~~~~~~~~~~~~~~~
And this is even more specific.

Topic 2
=======