fix: make ContentHeader subtitle optional (#542)

Author: fhlavac

packages/module/src/ContentHeader/ContentHeader.tsx

@@ -25,8 +25,8 @@ export interface PageHeaderLinkProps extends ButtonProps {
 export interface ContentHeaderProps {
   /** Title for content header */
   title: string;
-  /** Subtitle for content header */
-  subtitle: string;
+  /** Optional subtitle for content header */
+  subtitle?: string;
   /** Optional link below subtitle */
   linkProps?: PageHeaderLinkProps;
   /** Optional icon for content header (appears to the left of the content header's title with a divider) */
@@ -97,9 +97,11 @@ export const ContentHeader: React.FunctionComponent<React.PropsWithChildren<Cont
               </SplitItem>
             )}
           </Split>
-          <Content component="p" ouiaId={`${ouiaId}-subtitle`}>
-            {subtitle}
-          </Content>
+          {subtitle && (
+            <Content component="p" ouiaId={`${ouiaId}-subtitle`}>
+              {subtitle}
+            </Content>
+          )}
           {linkProps && (
             <Button variant={ButtonVariant.link} component="a" ouiaId={`${ouiaId}-link-button`} isInline icon={isExternal ? <ExternalLinkAltIcon className='pf-v6-u-ml-sm' /> : null} iconPosition="end" {...linkRestProps}>
               {linkProps.label}