Add docs Ultralytics 文档: - zh/index.md (#5871)

Signed-off-by: Glenn Jocher <glenn.jocher@ultralytics.com>
Co-authored-by: Laughing-q <1185102784@qq.com>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

docs/stylesheets/style.css

@@ -37,3 +37,8 @@ div.highlight {
     max-height: 20rem;
     overflow-y: auto; /* for adding a scrollbar when needed */
 }
+
+/* Set content width */
+.md-grid {
+  max-width: 1440px;
+}