translate title
translate 'Reader State and Update', 'Reader Monad primitive''
translate 'Sample Reader Computations'
もなど => monad
update Japanese translation of 'Reader state and update'
update translation of 'Reader Monad Primitive'
Update "Implementing the reader monad"

Change the translation of "trivial". (Use mathematic expression )
Update Reader state and update

Remove invalid char.
Update a expression to 'Computation'
Merge branch 'master' of https://github.com/posaunehm/update-monads_jp
Merge pull request #12 from posaunehm/master

Translate Chapter 4

fixed #4