Add docs for forking the project for customisation

docs/README.md

@@ -17,3 +17,4 @@ Documentation for specific topics can be found in the following files:
 * [Terms of Service and Privacy Policy](terms-of-service-and-privacy-policy.md)
 * [i18n](i18n.md)
 * [Colors and icons](colors-and-icons.md)
+* [Starting a new customisation project](starting-a-new-customisation-project.md)

docs/starting-a-new-customisation-project.md

@@ -0,0 +1,52 @@
+# Starting a new customisation project
+
+To start a new project to customise the Starter App, you should create a separate Git repository and
+setup the Git remotes so that you can pull in changes from the main (upstream) repository to your
+custom repository.
+
+## Fork the repository
+
+See the [Fork a repo](https://help.github.com/articles/fork-a-repo/) documentation.
+
+**Note:** If you want to make the fork to the same user, you have to start with an empty repository
+and follow the next steps in that repository.
+
+## Clone the fork
+
+Go to the directory where you want to clone the repository and run:
+
+```sh
+git clone git@github.com:YOUR_USERNAME/YOUR_FORK.git
+```
+
+## Set up remotes
+
+In your local fork repository, run:
+
+```sh
+git remote add upstream git@github.com:sharetribe/sharetribe-starter-app.git
+```
+
+See also the
+[Configuring a remote for a fork](https://help.github.com/articles/configuring-a-remote-for-a-fork/)
+documentation.
+
+## Pull in latest upstream changes
+
+In the `master` branch:
+
+1. Fetch the latest changes from the upstream repository:
+
+   ```sh
+   git fetch upstream
+   ```
+
+1. Merge the changes to your local branch
+
+   ```sh
+   git merge upstream/master
+   ```
+
+1. Fix possible merge conflicts, commit, and push/deploy.
+
+See also the [Syncing a fork](https://help.github.com/articles/syncing-a-fork/) documentation.