docs: Added enumName column option (typeorm#7570)

Added minor documentation for typeorm#4824

Author: jorenvandeweyer

docs/entities.md

@@ -569,6 +569,7 @@ You can change it by specifying your own name.
 * `charset: string` - Defines a column character set. Not supported by all database types.
 * `collation: string` - Defines a column collation.
 * `enum: string[]|AnyEnum` - Used in `enum` column type to specify list of allowed enum values. You can specify array of values or specify a enum class.
+* `enumName: string` - Defines the name for the used enum.
 * `asExpression: string` - Generated column expression. Used only in [MySQL](https://dev.mysql.com/doc/refman/5.7/en/create-table-generated-columns.html).
 * `generatedType: "VIRTUAL"|"STORED"` - Generated column type. Used only in [MySQL](https://dev.mysql.com/doc/refman/5.7/en/create-table-generated-columns.html).
 * `hstoreType: "object"|"string"` - Return type of `HSTORE` column. Returns value as string or as object. Used only in [Postgres](https://www.postgresql.org/docs/9.6/static/hstore.html).