Review "there's always more to learn" principle

# Review principle ["there's always more to learn"](https://github.com/DevInnovationLab/git-training/blob/main/texts/theres-always-more-to-learn.md) in the DIL Analytics Manual
- [ ] Review for style, typos, and readability. 
- [ ] If you have any suggestions or comments on the content, they're also very welcome.