Update README.md

Author: osamaakb

module3-crud-and-data-models/r1.1-principles-of-setting-up-your-schema/README.md

@@ -33,7 +33,7 @@ When a collection has a document, and, this document contains another document,
 
 When a value of a field in your table or collection referes to a value of another field in another table or collection.
 
-#### When to `Reference`
+#### When to Reference
 
 - If you need smaller documents or tables, your data will be separated across multiple documents or tables.
 - No duplicate of data.