RFR: 1463: Include starting branch in back port instructions

[Guoxiong Li]

Hi all,

This patch adds the suggested git command about fetching the newest code 
from the target branch before solving the conflicts.

Thanks for taking the time to review.

Best Regards,
-- Guoxiong

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Commit messages:
 - SKARA-1463

Changes: https://git.openjdk.org/skara/pull/1344/files
 Webrev: https://webrevs.openjdk.org/?repo=skara&pr=1344&range=00
  Issue: https://bugs.openjdk.org/browse/SKARA-1463
  Stats: 6 lines in 2 files changed: 5 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/skara/pull/1344.diff
  Fetch: git fetch https://git.openjdk.org/skara pull/1344/head:pull/1344

PR: https://git.openjdk.org/skara/pull/1344