In ROS 2 Introduction, some of the text is confusing especially for those not educated in software development. I think the following instances could be reworded to improve readability for those with little development experience:
Step 2: The sentence "Similar to web development frameworks such as Django or Ruby on Rails, ROS is a robotics development framework" isn't helpful for those who don't know what a development framework is and have never used the listed examples. I think that those for whom the references to Django and Ruby on Rails would be helpful don't need the explanation and for those who need the explanation, the references will increase confusion. I think this could be simplified to say "ROS is a robotics development framework" with the definition of framework on the following line.
Similar logic applies to other references to Django and Rails.
Step 3: I don't think the click mapping to highlight images works well. It doesn't follow external or internal consistency rules.
Step 3: You use the pub/sub architecture pattern to explain how ROS works. This works for people familiar with this pattern, but many are not. The link to the Wikipedia page is not helpful for those who aren't knowledgeable enough to parse the page. If pub/sub must be used in the explanation, I think providing your own simpler explanation (disconnected from ROS terminology) rather than relying on the Wikipedia page would be helpful.
Step 3: The last image doesn't seem to correspond well to the text.
Step 4: If the word 'topology' must be used, I think it should be defined.
In ROS 2 Introduction, some of the text is confusing especially for those not educated in software development. I think the following instances could be reworded to improve readability for those with little development experience: