Update step_four.md (#2629)

Windows users --like me-- may miss the period, and docker will not find `Dockerfile.txt.`
2017-04-07 15:29:27 -05:00 · 2017-04-07 15:29:27 -05:00 · 2365e5f3cc
parent 9d9e7493c5
commit 2365e5f3cc
1 changed files with 1 additions and 1 deletions
--- a/engine/getstarted/step_four.md
+++ b/engine/getstarted/step_four.md
@ -58,7 +58,7 @@ creating an image which runs on Linux.
    $ nano Dockerfile
    ```

-    **Windows**:
+    **Windows**: The `.` tells `notepad` not to add a `.txt` extension.

    ```none
    C:\> notepad Dockerfile.