include notes (#20)

* include notes

* Update README.md

Co-authored-by: arturovoltattorni <86232451+arturovoltattorni@users.noreply.github.com>

---------

Co-authored-by: arturovoltattorni <86232451+arturovoltattorni@users.noreply.github.com>

Author: edgardevo

README.md

@@ -74,5 +74,6 @@ df2looker --source-path my_dataform_project/dataform-compile.json --verbose
 
 ## Notes
 
-The tool currently supports BigQuery as the underlying database for Dataform.
-You might need to adjust the generated LookML code further to match your specific Looker project requirements.
+- The tool currently supports BigQuery as the underlying database for Dataform.
+- You might need to adjust the generated LookML code further to match your specific Looker project requirements.
+- This tool requires the BigQuery tables to exist, the reason is because Dataform doesn't provide schemas out of a compilation so it is not possible to know the schema of a table from the compilation alone.