Which Linux cross compile toolchain to use for 4.17?

Looks like this page is not updated for 4.17:

Can toolchain for 4.16 be used for 4.17?

As far as I can tell, yes. You can use the the same toolchain for 4.17 as 4.16 uses. (-v9 clang-4.0.0-based)

I am running a Linux dedicated server on 4.17 that I compiled using the 4.16 toolchain without issues.

Yes, it is the same as for 4.16 - I updated the wiki page.

Thanks for updating the wiki. Can the docs be updated as well? Cross-Compiling for Linux | Unreal Engine Documentation

This wikipage has updated info: A new, community-hosted Unreal Engine Wiki - Announcements - Epic Developer Community Forums

The 4.17 uses same toolchain but 4.18 uses new toolchain based on Clang 5.0.