Some minor fixes

[ghost]

I checked the first two chapters, so far I like it, but found some minor errors.

• [ ] also the img/Indentation.svg uses the old !!! syntax
• [ ] maybe you can check out this issue visionmedia/jade#1345 and write a little bit more info about the IE conditionals.
• [x] I don't think that Chapter 3's shorthand variable definition works but I may be wrong on this one (nope, I'm right, see: visionmedia/jade#1056)
• [ ] My english is not perfect but the sentence below the grunt image (Chapter 8) seems a little bit weird to me
• [ ] Chapter 9 - replace the "X volunteers" with real numbers.

I'll read the other chapters too, but I thought to share the stuff that I found already, so others don't have to be bothered by them.

Update: I finished reading the book. It was quite nice.

[notslang]

wow, really great fixes here. thanks a lot @netlovers!