Add example of NamePattern method implementation

[alexbudarov]

Environment

• Existing page: https://doc.cuba-platform.com/manual-7.1/entity_class_annotations.html#namePattern_annotation

Description of the bug or enhancement

Example of NamePattern with method does not show method implementation code. Why shouldn't we add implementation example, showing an idea of forming a non-trivial caption?

For example:

@NamePattern("#getCaption|gender,name")
...

public String getCaption() {
    String prefix = "";
    if (gender == Gender.MALE) {
        prefix = "Mr ";
    } else if (gender == Gender.FEMALE) {
        prefix = "Ms ";
    }
    return prefix + name;
}