Add section on target audience

[aturner-epcc]

Address comment from peer review

The target audience identified for the lesson is specific and realistic.
I am not sure I saw a section highlighting the target audience, has this been mentioned?

[jcohen02]

From offline discussion: A quick overview of the general target audience - people who are looking to develop their knowledge of container tooling to support the research work and enhacing reproducuiblity. Also note that this course is a beginner level course that is suitable for people who have no experience of containers.
Then provide more detail on specific roles that might benefit from this course - researchers, technical professionals - details of experience levels and areas of work.
Is there something in the new template for where this is supposed to fit?

[jcohen02]

Take a look at learner profiles in the new template. ( profiles directory with a profiles.md file in it).