docs: PySDM docs improvement

[AgnieszkaZaba]

@emmacware, @pawelmagnu, @Sfonxu, @olastrz

Notes from today's weekly meeting:

• add list of references (same as for PyMPDATA)
• add equations for sections in PySDM (maybe some general one). We can make separate issue for this or discussion on what equations will describe a section.
• add tags to a papers to make it easier to navigate.
• Create a list with notebook examples with short explanation what we can find inside - no need to open a notebook or a paper when navigating.
• Scaling plots to text width. #1434

Other issues connected to documentation:

• docs: fix link in pysdm_landing.md #1427
• docs: correct link to figs from Arabas 2023 #1426
• docs: Add a brief description of SDM #1429

[slayoo]

Thank you!
Other relevant issues worth mentioning here:

• docs: move logos from .github folder to docs/logos + add NCN, FNP, AGH logos to be included on the landing page #1428
• produce (and upload) the README animation on CI #1203
• Create an introductory example in docs #1152