update exercise description

README.md

@@ -1,5 +1,6 @@
 [![Build Status](https://travis-ci.org/coderefinery/forking-workflow-exercise.svg?branch=master)](https://travis-ci.org/coderefinery/forking-workflow-exercise/builds)
 
+## Distributed version control
 
 ## Exercise to practice collaborative forking workflow
 
@@ -8,7 +9,7 @@ We will run this exercise in groups. Groups can choose a number or a name.
 Objectives:
 
 - Learn how to fork, modify the fork, and file a pull request towards forked repo
-- Learn how to update your fork with upstream changes
+- Learn how to update your fork with upstream changes.
 
 
 ### Part A: Fork and clone
@@ -18,11 +19,13 @@ First fork this repository on GitHub into your namespace and then clone the fork
 
 ### Part B: Modify and commit
 
-Then add a file `group-X.py` where X is your group number or group name, e.g. `group-17.py`.
-**Add only one file per group**. (Why?)
+Before we do any modification, we create a new branch and switch to it - this is a good reflex and a good practice.
+On the new branch add a file `group-X.py` where X is your group number or group name, e.g. `group-17.py`.
+**Add only one file per group**.
+(Why? - if you are adventurous, add both a file with the same name to see what happens)
 
 This file should contain a function called `tweet()` which returns
-a string of maximum 280 characters, for instance:
+a string of maximum 280 characters, for instance (don't worry, nothing gets out to Twitter):
 
 ```python
 def tweet():
@@ -40,18 +43,23 @@ $ python main.py
 group 17 says: please replace this boring sentence with something more fun
 ```
 
+If it works, commit the change.
+
+
 ### Part C: Push your changes to the fork
 
-Once you see your sentence correctly printed, commit and push to your fork. Don't worry
+Once you see your sentence correctly printed, commit and push the branch to your fork.
+
+Don't worry
 nothing gets out to Twitter but please mind that your changes will be public on
 GitHub (but you can delete them later).
 
 
 ### Part D: File a pull request
 
-Then file a pull request towards the repository where you forked from.
+Then file a pull request from the branch on your fork towards the master branch on the repository where you forked from.
 
-Wait until we integrate all pull requests into the central repo
+Wait here until we integrate all pull requests into the central repo
 together on the big screen.
 
 
@@ -65,3 +73,6 @@ changes and verify that you got the files created by other groups:
 ```shell
 $ python main.py
 ```
+
+Make sure that the contributions from other groups are not only on your local repository
+but really also end up in your fork.