Update index.md, add signoff

remove an 'and' from 'and and'

Signed-off-by: Tim Whiteaker <[email protected]>

Author: twhiteaker

docs/tutorial/part-two/index.md

@@ -112,7 +112,7 @@ plugins.
 
 Let's start by creating a new site. At this point it probably makes sense to close the terminal windows you used to build tutorial-part-one so that you don't accidentally start building tutorial-part-two in the wrong place. If you don't close tutorial-part-one prior to building tutorial-part-two, you will see that tutorial-part-two appears at localhost:8001 instead of localhost:8000.
 
-Just like in part one, open a new terminal window and and run the following commands to create a new Gatsby site in a directory called `tutorial-part-two`. Then, change to this new directory:
+Just like in part one, open a new terminal window and run the following commands to create a new Gatsby site in a directory called `tutorial-part-two`. Then, change to this new directory:
 
 ```shell
 gatsby new tutorial-part-two https://github.com/gatsbyjs/gatsby-starter-hello-world