Translating PR878
[it] updating autocompletion output

As per PR #874
Update 01-chapter3.markdown

update sub-head Basic Branching and Merging and partially in sub-sub-header Basic Branching
Merge pull request #881 from daftano/master

[it] Updating translations
Merge pull request #883 from tamami/patch-1

Update 01-chapter3.markdown