docs: Cosmetic & functional fixes to comply with PDF generation req.

[cristianmihaipopa]

The purpose of this PR is to fix typos & mistakes that mess up the PDF generation of the doc. More changes will be added as soon as they are caught. PDF generation method is still in progress & is tested on a certain batch of pages that have different functionalities (collapsible content, math formulas etc.).

Doctools PDF output method PR was merged into main (analogdevicesinc/doctools#18).

PR Type

• Bug fix (change that fixes an issue)
• New feature (change that adds new functionality)
• Breaking change (has dependencies in other repos or will cause CI to fail)

PR Checklist

• I have followed the code style guidelines
• I have performed a self-review of changes
• I have compiled all hdl projects and libraries affected by this PR
• I have tested in hardware affected projects, at least on relevant boards
• I have commented my code, at least hard-to-understand parts
• I have signed off all commits from this PR
• I have updated the documentation (wiki pages, ReadMe files, Copyright etc)
• I have not introduced new Warnings/Critical Warnings on compilation
• I have added new hdl testbenches or updated existing ones

[IuliaCMoldovan]

Converted it as a draft PR since it is still WIP

[gastmaier]

I see you replaced my no-breaking hyphens with breaking hyphens (unicode inspect).
The purpose is to not allow a line break like this

32-
bit

The pdf tool does not support unicode or this unicode character?

[cristianmihaipopa]

The pdf tool does not support unicode or this unicode character?

Indeed, they don't support no-breaking hyphens. So far, I think only this unicode character is not supported. If no-breaking hyphens is messing up the page rendering (which in my case when I rendered the page it didn't, everything was fine), I will treat this case in code. Also, there're a few math formulas that don't render well too. This PR is only a draft and has the purpose to fix .rst mistakes so that no extra code for doctools is needed. For example, math formulas needed correction only in .rst. No need to implement correction mechanism in doctools.

[cristianmihaipopa]

I found out that separating .. math:: blocks which contain multiple math formulas, the PDF generation will be okay. For example, in this section (docs/library/spi_engine/instruction-fromat.rst line 81) we have this formulas:

.. math::

   delay_{before} = 2+ t * \frac{(div + 1)*2}{f_{clk}}

   delay_{after}  = t * \frac{(div + 1)*2}{f_{clk}}

If separated like this (also added '\' before '_{before}' ):

.. math::

   delay\_{before} = 2 + t * \frac{(div + 1)*2}{f_{clk}}

.. math::

   delay\_{after}  = t * \frac{(div + 1)*2}{f_{clk}}

The PDF generation will be okay. Even the HTML page will look fine.

[cristianmihaipopa]

docs/library/axi_ad485x: Tag <#hdl-regmap-DELAY_CNTRL> needs to be fixed

Will be changed to <#hdl-regmap-IO_DELAY_CNTRL> (the redirect to the below content will work then). Apparently tags likes this which are not working mess up the whole PDF generation (document is not readable by any program).

[gastmaier]

Please add rst2pdf.pdfbuilder to requirements.txt also