Modifying README.md to address ISSUE-53

[bmunroezappos]

No description provided.

[ruslanrusu]

here is what i needed to add

GRANT SELECT ON workflow to retool_readonly; GRANT SELECT ON workflow_run to retool_readonly; GRANT SELECT ON workflow_save to retool_readonly;

[mattharris-stripe]

Need two more table grants, but otherwise, it would be great to merge this in!

[julieechenn]

Good catch Ruslan and Matt! Accepted & merged

[bmunroezappos]

Thanks everyone!