Docs: Add detailed methods to docs

[berntpopp]

The documentation needs a detailed methods section describing the methods for each analysis/script and the data sources used. This should inlcude the following:

• [ ] PanelApp
• [ ] Literature
• [ ] Diagnostic Panels
• [ ] HPO/OMIM
• [ ] PubTator
• [ ] Merging of all sources
• [ ] Annotation with HGNC
• [ ] Annotation with ClinGen/GenCC
• [ ] Annotation with MONDO
• [ ] Annotation with ClinVar
• [ ] Annotation with OMIM
• [ ] Annotation with gnomAD data
• [ ] Computation of clinical groups
• [ ] Summary of the packages and versions used