Updated src/README.md to match building-features.md (#1672)
Updated src/README.md to match building-features.md (#1672)

* Adjust src/README.md to match building-features.md

* Change but to by.

falkencreative/toolkit-for-ynab,blargity/toolkit-for-ynab,blargity/toolkit-for-ynab,toolkit-for-ynab/toolkit-for-ynab,dbaldon/toolkit-for-ynab,dbaldon/toolkit-for-ynab,toolkit-for-ynab/toolkit-for-ynab,falkencreative/toolkit-for-ynab,dbaldon/toolkit-for-ynab,dbaldon/toolkit-for-ynab,toolkit-for-ynab/toolkit-for-ynab,toolkit-for-ynab/toolkit-for-ynab,falkencreative/toolkit-for-ynab,blargity/toolkit-for-ynab,falkencreative/toolkit-for-ynab,blargity/toolkit-for-ynab