fix(docs/tutorial/our-application): update index.md

Improve sentence clarity.

docs/tutorial/our-application/index.md

@@ -65,7 +65,7 @@ see a few flaws in the Dockerfile below. But, don't worry! We'll go over them.
     for the final image. Since we named the image `getting-started`, we can refer to that
     image when we run a container.
 
-    The `.` at the end of the `docker build` command tells that Docker should look for the `Dockerfile` in the current directory.
+    The `.` at the end of the `docker build` command tells Docker to look for the `Dockerfile` in the current directory.
 
 ## Starting an App Container