added some what is math stuff
last paragraph
Merge branch 'f-howtolearnmath' into develop
Pay our dues to LYAH.

I guess this accidentally got removed. Even if LYAH leaves a bit to be desired,
it is the motivation and namesake for the book, so we have to mention it.
Merge branch 'develop' into f-lyahcite
Move LYAH stanza to acknowledgements section
Merge pull request #72 from beingbrown/develop

Add a "How to learn math" section
Merge pull request #75 from pharpend/f-lyahcite

Pay our dues to LYAH.