backport 44936fd to other language and pdf

This change needs to be backported to all languages. The pdf toolchain
processes this formula with a transformation to some latex mathematic
typesetting and therefore needs to be updated.
Merge branch 'fix_math_typeset'
fix mis-translation private<-->public

 public.key is "公開鍵" and private.key is "秘密鍵" in Japanese.
[it] updated chapter 3
[it] Chapter 2: Reviewed 'Getting a Git Repository'
[it] Reviewed "Cloning an Existing Repository"
[it] Reviewed "Recording Changes to the Repository"
[it] Reviewed "Checking the Status of Your Files"
[it] Reviewed "Tracking New Files"
[it] Reviewed "Staging Modified Files"
[it] reviewed "Ignoring Files"
[it] Chapter 2

Reviewed "Viewing Your Staged and Unstaged Changes"
[it] Chapter 2

Reviewed "Committing Your Changes"
[it] Chapter 2

Skipping the Staging Area
[it] Reviewed "Removing Files"
Merge pull request #725 from daftano/master

[it] updated chapters 2 and 3
Update 01-chapter3.markdown

笔误修改

原文：You can take the changes on client that aren’t on server (C8 and C9) and replay them on your master branch by using the --onto option of git rebase
Merge pull request #726 from diceit/4-7

fix mis-translation private<-->public
Merge pull request #727 from lusecond/master

[zh] Update 01-chapter3.markdown
Merge branch 'progit/master'