docs(computed-properties.md): fix typo (#189)

* docs(computed-properties.md): fix typo * docs(computed-properties.md): fix typo in v3 directory * docs(stubbing-components.md): fix typo in v3 directory

Author: Thomasan1999

src/computed-properties.md

@@ -6,7 +6,7 @@ Find the Vue.js 3 version [here](/v3/).
 
 You can find the test described on this page [here](https://github.com/lmiller1990/vue-testing-handbook/tree/master/demo-app/tests/unit/NumberRenderer.spec.js).
 
-Testing computed properties are especially simple, since they are just plain old JavaScript functions.
+Testing computed properties is especially simple, since they are just plain old JavaScript functions.
 
 Let's start with looking at two different ways to test a `computed` property. We will develop a `<NumberRenderer>` component, that renders either odd or even numbers, based on a `numbers` computed property. 
 

src/v3/computed-properties.md

@@ -6,7 +6,7 @@ Find the Vue.js 2 version [here](/).
 
 You can find the test described on this page [here](https://github.com/lmiller1990/vue-testing-handbook/tree/master/demo-app-vue-3/tests/unit/NumberRenderer.spec.js).
 
-Testing computed properties are especially simple, since they are just plain old JavaScript functions.
+Testing computed properties is especially simple, since they are just plain old JavaScript functions.
 
 Let's start with looking at two different ways to test a `computed` property. We will develop a `<NumberRenderer>` component, that renders either odd or even numbers, based on a `numbers` computed property. 
 

src/v3/stubbing-components.md

@@ -83,7 +83,7 @@ export default {
 
 ## Write a test using `mount`
 
-Let's start off by writing a test to verify that `<ComponentWithAsyncCall>` is rendered. Note  that `findComponent` is used. `find` is used for querying DOM elements, and uses the `querySelector` syntax. `findComponent` is used when looking for a specific component, a takes a component as the argument.
+Let's start off by writing a test to verify that `<ComponentWithAsyncCall>` is rendered. Note that `findComponent` is used. `find` is used for querying DOM elements, and uses the `querySelector` syntax. `findComponent` is used when looking for a specific component, it takes a component as the argument.
 
 ```js
 import { shallowMount, mount } from '@vue/test-utils'