Update blog_custom_estimators.py
Update blog_custom_estimators.py

Added correct link to blogpost
Changed Sentosa to Setosa in a couple of places
cshallue/models,tombstone/models,tombstone/models,tombstone/models,jiaphuan/models,tombstone/models,cshallue/models,derekjchow/models,cshallue/models,alexgorban/models,tombstone/models,jiaphuan/models,jiaphuan/models,derekjchow/models,alexgorban/models,cshallue/models,derekjchow/models,derekjchow/models,jiaphuan/models,jiaphuan/models,alexgorban/models,alexgorban/models,tombstone/models,derekjchow/models,jiaphuan/models,cshallue/models,alexgorban/models