docs: add missing configuration pages and remove redundant H1 headers

contents/docs/configuration/general/index.mdx

@@ -0,0 +1,18 @@
+---
+title: General Settings
+description: Core store settings.
+---
+
+
+
+Located in **Appearance > General**.
+
+## SPA Mode
+Decide how much of your site uses our ultra-fast Single Page Application technology.
+*   **Disabled**: Use standard WordPress templates.
+*   **Checkout Only**: Normal browsing, fast checkout.
+*   **Full SPA**: The entire site is an app.
+
+## Container Width
+*   **Boxed (Recommended)**: Limits content width (max 1152px) for better readability.
+*   **Full Width**: Content stretches to the screen edges.