Tutorial: Minor fixes
Hi there!
I found the CMake Tutorial to be extremely helpful in learning how to use it, and I thought I would try and contribute some fixes to some simple issues I found.
NOTE: I wasn't totally sure how to generate HTML files from the .rst files, so I haven't actually validated that the output is what I'm expecting. (I tried building CMake, unsuprisingly it seems that website generation isn't part of a normal build.) I'm hoping at this point that the commits I've made are simple enough that someone else can take over from here.