keybase device remove --force-self gives "NIST token failed to verify" warning

# Steps to reproduce

* Create a Keybase user on the Keybase website, setting a username and password
* On a new computer (Ubuntu 20.04 in my case) install Keybase
* Launch Keybase
* Login to the Keybase app
* In the Keybase app create a paper key
* On the command line delete the device that you're on (so that only the paper key remains)

# Expected results

The current device is deleted

# Actual results

The current device is deleted and this warning is shown

```
$ keybase device remove --force-self "b2b16562ad80062be403361b49776518"
▶ INFO Revoking KIDs:
▶ INFO 012099db2d6b41aa2ced26efed7d75122c352273993862965122c92e2d5b8d255c850a
▶ INFO 012169de2567355f0b7988dcc2c1abdf92a09775dd396c714b982ac82ac5bc3a766b0a
▶ WARNING NIST token failed to verify [tags:ENG=MvEZqu2tnm8W,LU=D6ksdE9UlBnx,API=IKoNvJKMIAGi]
▶ WARNING NIST token failed to verify [tags:ENG=MvEZqu2tnm8W,LU=D6ksdE9UlBnx,API=zIBgKuGyesnO]
▶ WARNING NIST token failed to verify [tags:LU=D6ksdE9UlBnx,API=t-dxpH7SQpPf,ENG=MvEZqu2tnm8W]
```

It looks like this warning comes from [this line of code](https://github.com/keybase/kbfs/blob/a4a00254ce4a3f4cf9d19ca56085d4964f1a7f64/vendor/github.com/keybase/client/go/libkb/api.go#L570)

If this warning is expected and should show here, then this issue is probably more about adding either documentation or additional language to the warning so the user knows what it means (as I do not).

Reproduce the device removal with `keybase device remove --force-self` and inspect `vendor/github.com/keybase/client/go/libkb/api.go` around line 570, where the warning is reported. Determine whether the NIST token verification warning is expected during self-device removal. Done means the behavior is corrected or the warning clearly explains the outcome, with relevant validation added if an existing test location is found.

Written by the indexing model from the issue text.