Update README.md

adding some info about how to fill the spreadsheet correctly
Fixed Vinnie & Spike's Dead Seahorse Head:
* Fixed that first stage was ignored
* Uses now the upgrade instead of hard coded value
* Fixed interaction with Bag Full of Gold Fish
Revert "Fixed Vinnie & Spike's Dead Seahorse Head:"

This reverts commit a922460801579c0176681eb5bf59db2cc7c2f56c.
Merge branch 'master' of github.com:r0estir0bbe/nautsbuilder