Missing a new line after subtitles in ``Paragraph``

### Description of the modifications

Double new lines are not accepted in ``Paragraph`` element for rendering purpose.

However, a few titles don't render correctly due to this modification:
```
**Using PRNLD in a Spectrum or PSD Analysis ( ANTYPE, SPECTR)**
When using :ref:`prnld` in a spectrum analysis (after the combination file has been input through
:ref:`input`,,MCOM and when :ref:`spopt` has not been issued with ``Elcalc`` = YES during the
spectrum analysis), or in a PSD analysis when postprocessing 1-sigma results (loadstep 3, 4, or 5),
the following message will display in the printout header:
```

Previous example renders as:

### Useful links and references

Mentioned in https://github.com/ansys/pymapdl/pull/4003#discussion_r2142343640.

Start at the Paragraph rendering entry point and review the linked discussion in PR #4003, especially the reported subtitle case. Reproduce the example with the bold title and following text, then verify that the rendered output preserves a newline after subtitles without reintroducing unsupported double newlines.

Written by the indexing model from the issue text.