Hi. This page gives a 404:
https://docs.unrealengine.com/5.0/en-US/unreal-engine-programming-and-scripting/ProgrammingWithCPP/DownloadingSourceCode/
It’s the first result in for searching for “unreal engine source code”. the result link is:
https://docs.unrealengine.com/ProgrammingAndScripting/ProgrammingWithCPP/DownloadingSourceCode/
and I believe it should redirect to:
https://docs.unrealengine.com/5.0/en-US/downloading-unreal-engine-source-code/
instead.