[pt-br] Update chapter 3 git-branching

In line 53 'testing' is the name of branch
[it] reviewed chapter 1

Rewording for better understanding
Merge pull request #832 from kiide/master

[pt-br] Update chapter 3 git-branching
Merge pull request #834 from daftano/master

[it] reviewed chapter 1
[cs] translation revision of Chapter 2
Merge branch 'master' of https://github.com/progit/progit.git