E.g. I search “JetCommitTransaction”, search finds https://msdn.microsoft.com/en-us/library/gg269191(v=exchg.10).aspx which redirects to https://learn.microsoft.com/en-us/previous-versions/
That API is available in all versions of Windows starting from Win2000 to the very latest Win10, and even available for Windows 10 UWP apps, https://learn.microsoft.com/en-us/uwp/win32-and-com/win32-apis#apis-from-esentdll so it’s not deprecated or something.
archive.org works but it's slow and inconvenient.
Microsoft is moving all documentation from msdn.microsoft.com to learn.microsoft.com so I assume this will work itself out after a while but this is the first time I have seen a completely broken redirect.
I think Google cache and Archive.org are your best options for now. You could also try contacting @docsmsft/Github issues.