Typo in 3.1 under Add Git remote

## Location within the Course

* Section:3
* Lesson:1
* Language:en

## Description
Typo in "Add Git remote and push" section: "When you use `-u` option you set `origin master` as *upstream* and thus you can call after `git push` without the remote repo and branch."
Should be "When you use `-u` option you set `origin master` as *upstream*, and afterwards you can call `git push` without the remote repo and branch.

Open Section 3, Lesson 1 in the English course and locate the “Add Git remote and push” section. Compare the sentence containing the `-u` option with the correction in the issue, then update the wording and verify that the sentence reads clearly.

Written by the indexing model from the issue text.