Merge pull request #11812 from backstage/blam/fix-microsite

chore: fix microsite building

scripts/api-extractor.ts

@@ -40,7 +40,7 @@ import {
   TSDocTagSyntaxKind,
 } from '@microsoft/tsdoc';
 import { TSDocConfigFile } from '@microsoft/tsdoc-config';
-import { ApiPackage, ApiModel } from '@microsoft/api-extractor-model';
+import { ApiPackage, ApiModel, ApiItem } from '@microsoft/api-extractor-model';
 import {
   IMarkdownDocumenterOptions,
   MarkdownDocumenter,
@@ -939,6 +939,16 @@ async function buildDocs({
       this._markdownEmitter = new CustomCustomMarkdownEmitter(newModel);
     }
 
+    private _getFilenameForApiItem(apiItem: ApiItem): string {
+      const filename: string = super._getFilenameForApiItem(apiItem);
+
+      if (filename.includes('.html.')) {
+        return filename.replace(/\.html\./g, '._html.');
+      }
+
+      return filename;
+    }
+
     // We don't really get many chances to modify the generated AST
     // so we hook in wherever we can. In this case we add the front matter
     // just before writing the breadcrumbs at the top.