Updating documentation

[AnHeuermann]

Related Issues

Realted to OpenModelica/OpenModelica#10542

Purpose

• Fixing some warning for sphinx build of user's guide of OpenModelica

[AnHeuermann]

@arun3688 The OMSimulator User's Guide is broken for many API functions, where e.g. #CAPTION# is used, see e.g. https://openmodelica.org/doc/OMSimulator/master/html/api/setVariableStepSize.html.

We could remove those in this PR as well and fix the documentation.

[AnHeuermann]

The doc itself isn't broken, but the HTML files for each API functions should not be added to the final documentation.

[arun3688]

@AnHeuermann but we are not adding any html files, do you say that while building the documentation the html files are added ?

[AnHeuermann]

Looks like it. Maybe we add all .rst files at some place? What if we change them to be something like .rst.inc?

[arun3688]

@AnHeuermann, this is happening with your changes ?

[AnHeuermann]

The online documentation has an HTML file for each API function, see https://openmodelica.org/doc/OMSimulator/master/html/api/.
But I'm not sure why those files are generated in the first place. In doc/UsersGuide/source/conf.py only snippets from each api function.rst file are used.
I can try to change this in this PR as well.

[AnHeuermann]

Okay, now api/ is excluded from the spinx build. This also removes a bunch of warnings from the build.