feat(techdocs): use entity title as label in header

Signed-off-by: Phil Kuang <pkuang@factset.com>

.changeset/polite-ligers-hang.md

@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-techdocs': patch
+---
+
+Use entity title as label in `TechDocsReaderPageHeader` if available

.changeset/ten-wombats-reply.md

@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-techdocs-addons-test-utils': patch
+---
+
+Update default mock

plugins/techdocs-addons-test-utils/src/test-utils.tsx

@@ -82,7 +82,7 @@ type TechDocsAddonTesterOptions = {
 
 const defaultOptions: TechDocsAddonTesterOptions = {
   dom: <></>,
-  entity: {},
+  entity: { metadata: { name: '' } },
   metadata: {},
   componentId: 'docs',
   apis: [],

plugins/techdocs/src/reader/components/TechDocsReaderPageHeader/TechDocsReaderPageHeader.tsx

@@ -110,6 +110,7 @@ export const TechDocsReaderPageHeader = (
           <EntityRefLink
             color="inherit"
             entityRef={entityRef}
+            title={entityMetadata?.metadata.title}
             defaultKind="Component"
           />
         }