Fix typos (#865)

* docs: fix typo

* chore: fix typo

Author: toBeTheLight

packages/@vue/cli-plugin-pwa/__tests__/pwaPlugin.spec.js

@@ -33,7 +33,7 @@ test('pwa', async () => {
   expect(index).toMatch(/<link rel=preload [^>]+vendor[^>]+\.js>/)
   // should not preload manifest because it's inlined
   expect(index).not.toMatch(/<link rel=preload [^>]+manifest[^>]+\.js>/)
-  // should inline manifest and wepback runtime
+  // should inline manifest and webpack runtime
   expect(index).toMatch('webpackJsonp')
 
   // PWA specific directives

packages/@vue/cli-plugin-unit-mocha/README.md

@@ -26,7 +26,7 @@
 
   Default files matches are: any files in `test/unit` that end in `.spec.(ts|js)`.
 
-  All [mocha-wepback command line options](http://zinserjan.github.io/mocha-webpack/docs/installation/cli-usage.html) are also supported.
+  All [mocha-webpack command line options](http://zinserjan.github.io/mocha-webpack/docs/installation/cli-usage.html) are also supported.
 
 ## Configuration
 

packages/@vue/cli-service/__tests__/build.spec.js

@@ -29,7 +29,7 @@ test('build', async () => {
   expect(index).toMatch(/<link rel=preload [^>]+vendor[^>]+\.js>/)
   // should not preload manifest because it's inlined
   expect(index).not.toMatch(/<link rel=preload [^>]+manifest[^>]+\.js>/)
-  // should inline manifest and wepback runtime
+  // should inline manifest and webpack runtime
   expect(index).toMatch('webpackJsonp')
 
   const port = await portfinder.getPortPromise()