Catch GDSCN repos up so they can receive style updates

[KatherineCox]

Similar to #137, catch the existing GDSCN repos up to match AnVIL_Template's GDSCN styling, so they can smoothly receive future updates

• [x] jhudsl/GDSCN_Book_SARS_Galaxy_on_AnVIL
• [x] jhudsl/GDSCN_Book_Statistics_for_Genomics_Differential_Expression - PR is breaking: https://github.com/jhudsl/GDSCN_Book_Statistics_for_Genomics_Differential_Expression/pull/20
• [x] jhudsl/GDSCN_Book_Statistics_for_Genomics_scRNA-seq - PR is breaking: https://github.com/jhudsl/GDSCN_Book_Statistics_for_Genomics_scRNA-seq/pull/11
• [ ] jhudsl/GDSCN_Book_Statistics_for_Genomics_RNA-seq
• [x] jhudsl/GDSCN_Book_Statistics_for_Genomics_PCA

[KatherineCox]

Don't forget to delete old style-sets - this won't be done automatically. Also check spellcheck dictionary - remove fyi And date format in index.Rmd

• [x] jhudsl/GDSCN_Book_SARS_Galaxy_on_AnVIL
• [x] jhudsl/GDSCN_Book_Statistics_for_Genomics_Differential_Expression
• [x] jhudsl/GDSCN_Book_Statistics_for_Genomics_scRNA-seq
• [ ] jhudsl/GDSCN_Book_Statistics_for_Genomics_RNA-seq
• [x] jhudsl/GDSCN_Book_Statistics_for_Genomics_PCA
• [x] AnVIL_Book_WDL
• [ ] AnVIL_Book_Getting_Started
• [ ] phylogenetic-techniques
• [ ] AnVIL_Book_Instructor_Guide
• [x] fhdsl/AnVIL_Book_Epigenetics_Intro