fix trailing slash mismatch in dev vs build in docs example (#4912)

examples/docs/src/components/LeftSidebar/LeftSidebar.astro

@@ -7,7 +7,7 @@ type Props = {
 };
 
 const { currentPage } = Astro.props as Props;
-const currentPageMatch = currentPage.slice(1);
+const currentPageMatch = currentPage.endsWith('/') ? currentPage.slice(1, -1) : currentPage.slice(1);
 const langCode = getLanguageFromURL(currentPage);
 const sidebar = SIDEBAR[langCode];
 ---