Fix typo in Windows Build Instructions

docs/windows_build_instructions.md

 # Checking out and Building Chromium for Windows
 
 There are instructions for other platforms linked from the 
 [get the code](get_the_code.md) page.
 
 ## Instructions for Google Employees
 
 Are you a Google employee? See
 [go/building-chrome](https://goto.google.com/building-chrome) instead.
 
@@ skipping 81 matching lines @@
 long as the full path has no spaces):
 
 ```shell
 $ mkdir chromium && cd chromium
 ```
 
 Run the `fetch` tool from `depot_tools` to check out the code and its
 dependencies.
 
 ```shell
-$ fetch ios
+$ fetch chromium

[Dirk Pranke, 2016/12/04 22:05:31]

Whoops, yes :).

 ```
 
 If you don't want the full repo history, you can save a lot of time by
 adding the `--no-history` flag to `fetch`.
 
 Expect the command to take 30 minutes on even a fast connection, and many
 hours on slower ones.
 
 When `fetch` completes, it will have created a hidden `.gclient` file and a
 directory called `src` in the working directory. The remaining instructions
@@ skipping 114 matching lines @@
 $ gclient sync
 ```
 
 The first command updates the primary Chromium source repository and rebases
 any of your local branches on top of tip-of-tree (aka the Git branch `origin/master`).
 If you don't want to use this script, you can also just use `git pull` or 
 other common Git commands to update the repo.
 
 The second command syncs the subrepositories to the appropriate versions and
 re-runs the hooks as needed.