NETCONF testtool user guide still contains references to removed bierman-02 paths: `/restconf/config`, `/restconf/operational` and `/restconf/operations`. Replace them with `/rests/data` and `/rests/operations`. Fix paths according to RFC 8040 (for example topology keys usage).

In addition, paths to build testtool are no more valid.

Also, remove `Tip` which contains download link to old Sodium SR2 version without replacement.

The docs is available at: https://docs.opendaylight.org/projects/netconf/en/latest/testtool.html.

Try to read and if possible retest instructions - if applicable we should create new tasks.