net: document IsNotFound field
After CL 534937, the IsNotFound field is set to true on
nodata and NXDOMAIN conditions consistently across systems
and all lookup methods.
Change-Id: I419d1c818f17e915cee4959c3a9ac92c2e4bb92c
GitHub-Last-Rev:
59c537fc0626bfa959f43f9e9958f7af0e54ca55
GitHub-Pull-Request: golang/go#63654
Reviewed-on: https://go-review.googlesource.com/c/go/+/536775
Reviewed-by: Damien Neil <dneil@google.com>
Auto-Submit: Damien Neil <dneil@google.com>
Reviewed-by: David Chase <drchase@google.com>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>