Add omitzero mention in README

Author: System-Glitch

README.md

@@ -279,7 +279,7 @@ It is important to make sure your JSON expression returns a value that has a typ
 
 ### Model and DTO recommendations
 
-- Use `json:",omitempty"` on all DTO fields.
+- Use `json:",omitempty"` on all DTO fields. (or `json:",omitzero"` for struct fields like `time.Time`)
 	- *Note: using `omitempty` on slices will remove them from the json result if they are not nil and empty. There is currently no solution to this problem using the standard json package.*
 - Don't include the foreign keys in the DTO.
 - Use `*null.Time` from the [`gopkg.in/guregu/null.v4`](https://github.com/guregu/null) library instead of `sql.NullTime`.