In the standard library docs, you can view the name, type signature, and description of a library function, but there is no easily discoverable way to find its implementation (definition). For example, if I want to find out how isLeapYear is implemented, I have to manually go to the Daml compiler GitHub repo and search for it.
Hackage and many other programming documentation sites already have source link annotations, where the docs page is automatically populated with links to the source code of each module, function, class, etc. I believe this would be a popular and useful feature for the Daml Documentation site to have as well.