make icons page lowercase and fix shorthands link

Author: LFDanLu

packages/dev/s2-docs/pages/s2/index.mdx

@@ -49,7 +49,7 @@ export const title = 'Home';
   {id: 'Divider', name: 'Divider', href: 'Divider.html'},
   {id: 'DropZone', name: 'DropZone', href: 'DropZone.html'},
   {id: 'Form', name: 'Form', href: 'Form.html'},
-  {id: 'Icons', name: 'Icons', href: 'Icons.html'},
+  {id: 'Icons', name: 'Icons', href: 'icons.html'},
   {id: 'IllustratedMessage', name: 'IllustratedMessage', href: 'IllustratedMessage.html'},
   {id: 'Illustrations', name: 'Illustrations', href: 'Illustrations.html'},
   {id: 'Image', name: 'Image', href: 'Image.html'},

packages/dev/s2-docs/pages/s2/reference.mdx

@@ -37,7 +37,7 @@ Size props like `width` and `height` accept arbitrary pixel values. Values are c
 
 ## Text
 
-Spectrum 2 typography can be applied via the `font` [shorthand](#shorthand), which sets `fontFamily`, `fontSize`, `fontWeight`, `lineHeight`, and `color`. You can override any of these individually.
+Spectrum 2 typography can be applied via the `font` [shorthand](#shorthands), which sets `fontFamily`, `fontSize`, `fontWeight`, `lineHeight`, and `color`. You can override any of these individually.
 
 ```tsx
 <main>

packages/dev/s2-docs/pages/s2/styling.mdx

@@ -300,7 +300,7 @@ function MyComponent({isQuiet, styles}: {isQuiet?: boolean, styles?: StyleString
 <MyComponent styles={userStyles} />
 ```
 
-The `iconStyle` macro should be used when styling Icons, see the [docs](./Icons.html#iconstyle) for more information.
+The `iconStyle` macro should be used when styling Icons, see the [docs](./icons.html#iconstyle) for more information.
 
 ## CSS optimization