chore(Introduction): s/Github/GitHub/
chore(about-author): s/Github/GitHub/
chore(beginning-story): s/Github/GitHub/(except slide title)
chore(all): fix typos
chore(Introduction): s/ES6 Promise/ES6 Promises/
chore(promise-library): s/ES6 Promise/ES6 Promises/
Merge pull request #166 from syoichi/pr1-typo

fix(): fix typo

s/Github/GitHub/ & s/ES6 Promise/ES6 Promises/