Added a small amount of text for people looking to get started but are not aware of gitflow

[Rosencrantz]

Added a reference and link to further information on Gitflow. Also added a small link from the README file to the contributing file so people know where to look when getting started with Aleph develolpment.

[tillprochaska]

I’d suggest to add the following code at the very beginning of the readme to clarify that the default branch contains unreleased code.

⚠️ **IMPORTANT** ⚠️ The default branch in this GitHub repository is "develop". The develop branch contains unreleased, unstable code. For stable releases, please check out the `list of releases <https://github.com/alephdata/aleph/releases>`_ or switch to the `main branch <https://github.com/alephdata/aleph/tree/main>`_.

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[tillprochaska]

@Rosencrantz Would you mind elaborating what the 😕 emoji means? ;)

[Rosencrantz]

@Rosencrantz Would you mind elaborating what the 😕 emoji means? ;)

It makes me sad that we have to pitch things at this level.

[tillprochaska]

Fixed a small issue with the markup (there needs to be an empty line between the heading and the following paragraph, otherwise it doesn’t render correctly).