fix some formatting of web-push doc

web-push.md

@@ -12,7 +12,7 @@ controlling the web browser's source code. Here named PROVIDER. An example of a
 PROVIDER is FCM (Firebase Cloud Messaging) which is owned by Google.
 3) The Web Application that a user is visiting from their web browser. Let's
 call this the SERVICE (short for Web Push application service)
-[4) A Custom Web Push Intermediary Service, either third party or self-hosted.
+4) A Custom Web Push Intermediary Service, either third party or self-hosted.
 Called INTERMEDIARY here. FCM also may fit in this category if the SERVICE
 has an API key from FCM.]
 
@@ -105,7 +105,7 @@ Here's a version which can be used for testing locally.  Note there can be
 caching issues in your browser!  Incognito is highly recommended.
 
 sw-dev.ts
-
+```
 self.addEventListener('push', function(event: PushEvent) {
   console.log('Received a push message', event);
 
@@ -122,10 +122,11 @@ self.addEventListener('push', function(event: PushEvent) {
     })
   );
 });
+```
 
 
 vue.config.js
-
+```
 module.exports = {
   pwa: {
     workboxOptions: {
@@ -133,6 +134,7 @@ module.exports = {
     }
   }
 }
+```
 
 Once we have the service worker registered and the ServiceWorkerRegistration is
 returned, we then have access to a `pushManager` property object.  This property
@@ -184,6 +186,7 @@ PROVIDER which creates and stores a special URL for that BROWSER.
 
 Here's a bit of code describing the above process:
 
+```
 // b64 is the VAPID
 b64 = 'BEl62iUYgUivxIkv69yViEuiBIa-Ib9-SkvMeAtA3LFgDzkrxZJjSgSnfckjBJuBkr3qBUYIHBQFLXYp5Nksh8U';
 const applicationServerKey = urlBase64ToUint8Array(b64);
@@ -199,6 +202,7 @@ registration.pushManager.subscribe(options)
   .catch(function(error) {
     console.error('Push subscription failed:', error);
   });
+```
 
 In this example, the `applicationServerKey` variable contains the VAPID public
 key, which is converted to a `Uint8Array` using a function such as this:
@@ -266,6 +270,7 @@ via the PROVIDER so that they reach the BROWSER service worker.
 Just to remind us that in our service worker our code for receiving messages
 will look something like this:
 
+```
 self.addEventListener('push', function(event: PushEvent) {
   console.log('Received a push message', event);
 
@@ -282,7 +287,7 @@ self.addEventListener('push', function(event: PushEvent) {
     })
   );
 });
-
+```
 
 
 Now to address the issue of receiving notification messages on mobile devices.