Restructure and populate documentation

Replace template placeholder docs with real content:
- Home page with feature overview and quick example
- Installation guide (pip, source, uv, optional deps)
- Quickstart with examples for all endpoints and features
- API reference via mkdocstrings (all public classes/functions)
- Vignettes placeholder for future notebooks
- Simplified About page with citation

Removes unused community, learn, explanation, and project
philosophy sections from the template.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: deeenes

docs/about.md

@@ -1,3 +1,27 @@
 # About
 
-This project was created by OmniPath Team.
+omnipath-client is developed by the
+[Saez-Rodriguez group](https://saezlab.org/) at Heidelberg University Hospital.
+
+## Links
+
+- **Source code**: [github.com/saezlab/omnipath-client](https://github.com/saezlab/omnipath-client)
+- **OmniPath**: [omnipathdb.org](https://omnipathdb.org/)
+- **API**: [dev.omnipathdb.org](https://dev.omnipathdb.org/)
+- **Issues**: [github.com/saezlab/omnipath-client/issues](https://github.com/saezlab/omnipath-client/issues)
+
+## License
+
+BSD-3-Clause. See the
+[LICENSE](https://github.com/saezlab/omnipath-client/blob/master/LICENSE)
+file for details.
+
+## Citation
+
+If you use OmniPath data in your research, please cite:
+
+> Turei D, Valdeolivas A, Gul L, Palacio-Escat N, Klein M, Ivanova O,
+> Olbei M, Gabor A, Theis F, Korcsmaros T, Saez-Rodriguez J. (2021)
+> Integrated intra- and intercellular signaling knowledge for multicellular
+> omics analysis. *Molecular Systems Biology* 17:e9923.
+> [doi:10.15252/msb.20209923](https://doi.org/10.15252/msb.20209923)