docs(next/script): Improve formatting of docs (vercel#26149)

Noticed a few things off in the Script docs—for example, the "before" variant should show using a non-React Component `<script>` tag, & the capitalization was inconsistent in a few places.

## Documentation / Examples

- [x] Make sure the linting passes

docs/basic-features/script.md

@@ -12,7 +12,7 @@ Example of usage
 import Script from 'next/script'
 
 // Before
-<Script
+<script
   async
   src="https://www.google-analytics.com/analytics.js"
 />
@@ -36,28 +36,27 @@ Three loading strategies will be initially supported for wrapping third-party sc
 
 NOTE: above strategies work the same for inline scripts wrapped with ScriptLoader.
 
-Example scenarios
+## Example scenarios
 
 ```js
 import Script from 'next/script'
 
-
 // Loading polyfills before-interactive
 <Script
   src="https://polyfill.io/v3/polyfill.min.js?features=IntersectionObserverEntry%2CIntersectionObserver"
   strategy="beforeInteractive"
-></Script>
+/>
 
 // Lazy load FB scripts
 <Script
   src="https://connect.facebook.net/en_US/sdk.js"
   strategy="lazyOnload"
-></Script>
+/>
 
 // Use the onLoad callback to execute code on script load
 <Script id="stripe-js" src="https://js.stripe.com/v3/" onLoad={() => {
   this.setState({stripe: window.Stripe('pk_test_12345')});
-}}></Script>
+}} />
 
 // Loading strategy works for inline scripts too
 <Script strategy="lazyOnload">
@@ -78,7 +77,7 @@ import Script from 'next/script'
   id="analytics"
   nonce="XUENAJFW"
   data-test="analytics"
-></Script>
+/>
 ```
 
 ## Which third-party scripts to wrap with Script Loader
@@ -89,4 +88,4 @@ We recommend the following Script Loader strategies for these categories of thir
 | ----------------- | -------------------------------------------------------------------------------------------- |
 | beforeInteractive | polyfill.io<br>Bot detection, security & authentication<br>User consent management (GDPR)    |
 | afterInteractive  | Tag-managers<br>Analytics                                                                    |
-| lazyOnload        | customer relationship management eg. Google feedback, chat support widget<br>social networks |
+| lazyOnload        | Customer relationship management eg. Google feedback, chat support widget<br>Social networks |