cr_chains: fix comment typo
cr_chains: fix comment typo

Found by @akalin-keybase.

Issue: KBFS-1473

keybase/kbfs,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/kbfs,keybase/client,keybase/client,keybase/client,keybase/kbfs,keybase/client,keybase/kbfs,keybase/client,keybase/client