docs: improvements to API reference intro sections (#9397)

- Improve intro sections of API reference to utilize divided columns
- Improve the content of the intro sections
- Add a new Workflows section to explain the workflows badge and how to use it
- Fixes to headings and add anchor for copying the link to a section
- Fixes responsiveness of intro sections on mobile devices
- Other: fix loading not showing when a sidebar category is opened.

Closes DOCS-932, DOCS-934, DOCS-937

Preview: https://api-reference-v2-git-docs-api-ref-intro-fixes-medusajs.vercel.app/v2/api/store

www/packages/docs-ui/src/components/Sidebar/Item/Category/index.tsx

@@ -29,18 +29,21 @@ export const SidebarItemCategory = ({
     getPersistedCategoryState,
     persistState,
   } = useSidebar()
+  const itemShowLoading = useMemo(() => {
+    return !item.loaded || (item.showLoadingIfEmpty && !item.children?.length)
+  }, [item])
 
   useEffect(() => {
-    if (open && !item.loaded) {
+    if (open && itemShowLoading) {
       setShowLoading(true)
     }
-  }, [open])
+  }, [open, itemShowLoading])
 
   useEffect(() => {
-    if (item.loaded && showLoading) {
+    if (!itemShowLoading && showLoading) {
       setShowLoading(false)
     }
-  }, [item])
+  }, [itemShowLoading, showLoading])
 
   useEffect(() => {
     const isActive = isChildrenActive(item)