update Readme

Author: djarecka

linkml-schema/source_library_generation/README.md

@@ -1,4 +1,5 @@
 ## Sources to build the library geenration model
 
 - Metadata from [Google Sheet](https://docs.google.com/spreadsheets/d/11OcQz1Vk3ofny3Ql7wN-XlHkZwub-hojt-fO094SxiI/edit?usp=sharing)
+- All the sheets will be saved as tsv files in `gsheet_output`
 - Current Google Sheet version: `bk_workshop_mit24`