Rename "secret variables"
We have something called "secret variables" which are named that way because the variables and their values are not in source control, thus hidden from viewers. But they're not exactly "secret", and that name isn't really intuitive. We should change it to something better that more accurately reflects what they are.
In some places we call them "project variables and group variables", but that's a bit of a mouth full. Other vendors call them "environment variables", and that's the leading candidate. But "environment variables" is still a bit tricky because there are multiple environments we're talking about. Not only do we have a feature called environments (staging, production, etc.), but there's also the difference between the environment that the job runs in during CI/CD, and the environment your app runs in (in Docker, for example). To make it more complicated, there are also variables we pass to Helm with Auto DevOps.
Rename Secret Variables into just Variables. This is fine when it is clear the scope of the variable (project, group) for example in the settings page, or when this is not something that should be mentioned.
When we need to differentiate, we can explicitly say Project Variables or Group Variables.
We need to rename all occurrences in both the product interface and in the documentation.
This issue will address just the rename operation and will not impact the availability of variables in different places.