Doc update

[hiker]

I had two comments from my last PSyclone training that we should try to address:

1. The documentation of the symbol table is not complete, only some methods are documented in the doc (some in users guide, some in devs guide). The obvious solution is to use the ref guide, but I wonder if it is on purpose that we only document selected functions of the symbol table?
2. It would be useful if we have a kind of 'table of content' for all transformations. If you look for something but are not certain about the name, it involves a lot of scrolling since the transformation names are not listed (no subsection for 'Available Transformations). Could we perhaps either add this on the left-hand-side where sub(sub) sections are listed, or maybe add a simple table at the beginning of this chapter with links?

[arporter]

To avoid duplication/work I'd be tempted to just point people to the Reference Guide as that is automatically kept up-to=date. @sergisiso might have a view on this though.

I fully agree with point 2 - it's not very good (and I normally revert to the ReferenceGuide again). Having it on the LHS would be great if possible but, failing that, a table would also be useful.

[sergisiso]

I agree we should point (or embed) the reference_guide, and make the docstring there the only "source-of-true" with an example of the transformation, we already have many transformations with this format.

As Andy suggests I would invest some time to look at making the "list of methods" / "list of transformations" also come from thet the docstrings directly and be part of the "index"/"menu". A quick google search pointed to https://www.sphinx-doc.org/en/master/usage/extensions/autosummary.html with the toctree option. But I am unsure if this is what we need.