chore(docs): fix commas and tweak small issues in tutorial

docs/tutorial/part-three/index.md

@@ -7,7 +7,7 @@ Welcome to part three!
 
 ## What's in this tutorial?
 
-In this part, you'll learn about Gatsby plugins, and creating "layout" components.
+In this part, you'll learn about Gatsby plugins and creating "layout" components.
 
 Gatsby plugins are JavaScript packages that help add functionality to a Gatsby site. Gatsby is designed to be extensible, which means plugins are able to extend and modify just about everything Gatsby does.
 
@@ -31,7 +31,7 @@ For an initial introduction to using plugins, we'll install and implement the Ga
 
 ### ✋ Create a new Gatsby site
 
-As we mentioned in [part two](/tutorial/part-two/), at this point it's probably a good idea to close the terminal window(s) and project files from previous parts of the tutorial, to keep things clean on your desktop. Then, open a new terminal window and run the following commands to create a new Gatsby site in a directory called `tutorial-part-three` and then move to this new directory:
+As we mentioned in [part two](/tutorial/part-two/), at this point it's probably a good idea to close the terminal window(s) and project files from previous parts of the tutorial, to keep things clean on your desktop. Then open a new terminal window and run the following commands to create a new Gatsby site in a directory called `tutorial-part-three` and then move to this new directory:
 
 ```shell
 gatsby new tutorial-part-three /~https://github.com/gatsbyjs/gatsby-starter-hello-world
@@ -50,7 +50,7 @@ npm install --save gatsby-plugin-typography react-typography typography typograp
 
 > Note: Typography.js requires a few additional packages, so those are included in the instructions. Additional requirements like this will be listed in the "install" instructions of each plugin.
 
-2. Create a new file in the root of your project called `gatsby-config.js`, and copy the following into the file:
+2. Create a new file in the root of your project called `gatsby-config.js` and copy the following into the file:
 
 ```javascript:title=gatsby-config.js
 module.exports = {
@@ -69,7 +69,7 @@ The `gatsby-config.js` is another special file that Gatsby will automatically re
 
 > Check out the [doc on gatsby-config.js](/docs/gatsby-config/) to read more, if you wish.
 
-3. Typography.js needs a configuration file. Create a new directory called `utils` in the `src` directory. Then add a new file called `typography.js` to `utils`, and copy the following into the file:
+3. Typography.js needs a configuration file. Create a new directory called `utils` in the `src` directory. Then add a new file called `typography.js` to `utils` and copy the following into the file:
 
 ```javascript:title=src/utils/typography.js
 import Typography from "typography"
@@ -138,7 +138,7 @@ Sweet. You've installed and configured your very first Gatsby plugin!
 
 ## Creating layout components
 
-Now let's move on to learning about layout components. To get ready for this part, add a couple new pages to your project: an about page, and a contact page.
+Now let's move on to learning about layout components. To get ready for this part, add a couple new pages to your project: an about page and a contact page.
 
 ```jsx:title=src/pages/about.js
 import React from "react"
@@ -213,7 +213,7 @@ But try navigating to `/about/`, or `/contact/`. The content on those pages stil
 
 4. Import the layout component in `about.js` and `contact.js` (as you did for `index.js` in the previous step).
 
-The content of all three of your pages is centered, thanks to this single shared layout component!
+The content of all three of your pages is centered thanks to this single shared layout component!
 
 ### ✋ Add a site title.
 
@@ -230,7 +230,7 @@ export default ({ children }) => (
 )
 ```
 
-If you go to any of your three pages you'll see the same title added e.g. the `/about/` page:
+If you go to any of your three pages, you'll see the same title added, e.g. the `/about/` page:
 
 ![with-title](with-title.png)