API docs for revoke do not work if token has `+` character

[Steve-Mcl]

REF: https://discourse.nodered.org/t/node-red-token-revokation/69881/4?u=steve-mcl

The example to revoke shown here > https://nodered.org/docs/api/admin/oauth#revoking-the-token < fails to logout a user if the data token contains a + character.

Assuming nothing has changed other than being lucky enough to get a token with a + char then we should probably update the example to use --data-urlencode

Also, make clear that the data part token is the token of the user to log out.

e.g.

curl --data-urlencode 'token=USER_TO_LOG_OUT_SECRET_TOKEN' -H "Authorization: Bearer ANY_USER_SECRET_TOKEN" http://localhost:1880/auth/revoke