Add more literature

[MakisH]

This PR:

• Links more waveform iteration resources from the literature guide (fyi @BenjaminRodenberg):
  • https://doi.org/10.1002/nme.70063
  • https://doi.org/10.48550/arXiv.2511.07616
• Adds the workshops paper (together with a BibTeX file) in the "Organizing a preCICE Workshop" page and links to that page from the workshops overview page
  • https://doi.org/10.14279/eceasst.v85.2700