add git collaborating task (#1454)

* add git collaborating task

* Update git-collaboration/README.md

Co-authored-by: Daniel Wagner-Hall <dawagner@gmail.com>

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Co-authored-by: Daniel Wagner-Hall <dawagner@gmail.com>

Author: cifarquhar

git-collaboration/README.md

@@ -0,0 +1,51 @@
+# Git Collaboration
+
+## Learning Objectives
+
+<!--{{<objectives>}}>-->
+
+- [ ] Collaborate with colleagues using Git
+<!--{{<objectives>}}>-->
+
+It's very unlikely that you will be the only person working with a Git repository. We have already practised creating branches and merging on our own during the prep, now we will do it with another person.
+
+**You will need to find a partner for this exercise**. If you have an odd number of people in your cohort you can work in a three, the important thing is that you work on a different repository for parts 1 and 2.
+
+## Instructions
+
+### Part 1 - Creating the repository
+
+1. Create a new directory called `animal-website` and an `index.html` file inside it.
+2. Initialise a Git repository and commit the empty file.
+3. Create a repository on GitHub and link it to your local repository
+4. Populate `index.html` file with some information about your favourite animal. You should include:
+   - A title
+   - Two or three sentences about the animal. You can copy something from the internet if you like.
+   - A picture of the animal
+   - An unordered list with three facts about the animal, eg. its habitat, its diet, etc
+5. Remember to commit your changes often!
+6. When you have built the site push the changes to GitHub and send the repository's url to your partner.
+7. You will need to add your partner as a collaborator on your repository before they can push to it. Click the `Settings` tab on the repository page then go to the `Collaborators and teams` page, then click `Add people` and enter your partners username. They will get an invite which they need to accept.
+
+### Part 2 - Collaborating
+
+1. Accept the invitation to collaborate from your partner
+2. Clone the repository to your computer
+3. Create a branch called `add-css`. Check that you are now working on your new branch.
+4. Create a `styles.css` file and add it to `index.html` using a `<link>` element.
+5. Add the following styling to the page:
+   - Change the background colour
+   - Change the font
+   - Center the title
+   - Add a border to the image
+6. Remember to commit after each change!
+7. Push your branch to GitHub
+8. Create a pull request asking to merge your branch to `main`
+
+### Part 3 - Merging
+
+1. At this point your partner should have created a pull request. Merge the changes into your `main` branch.
+2. **If you see a message about merge conflicts stop here**. That means something has gone wrong somewhere in this process. Post a message in Slack to ask for help.
+3. You can **pull** the changes to your laptop to see what's different in the website. Click the three dots next to teh repository name in the source control tab and click "pull".
+
+If you see your partner's changes in your browser then everything has worked, well done! If not then you can post in Slack and ask for help, or speak to a volunteer in class. You should definitely speak to your partner and make sure nobody missed anything while working through the exercise.