FWIW I’ve found that Google searching for the Addressables documentation will lead to 0.4 rather than latest. Definitely recommend checking which version you are on if you continue to access through Google, or using the documentation button from the Package Manager.
This happened to me too! I spent several days trying to make sense of the documentation that I found on Google (which happened to be for 0.4) before finding out that I should have been reading from the 1.2 version. It would be nice if the documentation was like docs.unity3d.com where it explicitly indicates that the old version is being viewed and giving the option to review the newer one.
To make your life easier, if you cannot find the documentation on the website, documentation is actually bundled in all packages, at <package path>/Documentation~. Unless you have explicitly imported a package into ProjectPath/Packages/, that will be ProjectPath/Library/PackageCache/<Package>/Documentation~. You can use any .md viewer to browse it.