doc/user/install-operator-sdk.md: specify gpg --keyserver
@@ -47,6 +47,12 @@ To download the key, use the following command, replacing `$KEY_ID` with the RSA
$ gpg --recv-key "$KEY_ID"
```
+You'll need to specify a key server if one hasn't been configured. For example:
+
+```sh
+$ gpg --keyserver keyserver.ubuntu.com --recv-key "$KEY_ID"
+```
+
Now you should be able to verify the binary.
