Fix typo in the html generation instructions. (#412)

* Fix typo in the html generation instructions.

* Add a code block for the GLFW window pointer.

Almost all of the code listed in this chapter uses a c++ code block. The
block for the 'GLFWWindow* window' was missing.

Author: ladysadie

README.md

@@ -124,7 +124,7 @@ necessary.
 Now with the above done, we can generate the static files. Asuming the daux.io
 and VulkanTutorial directories are next to each other, go into the `daux.io`
 directory and run a command similar to:
-`php generate -s ../VulkanTutorial -d ../VulkanTutorial/out`.
+`daux generate -s ../VulkanTutorial -d ../VulkanTutorial/out`.
 
 `-s` tells it where to find the documentation, while `-d` tells it where to put
 the generated files.