[code-reflection] Integrated: Update readme

[Paul Sandoz]

Include some details specific to Babylon source.

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Commit messages:
 - Remove trailing WS
 - Update readme

Changes: https://git.openjdk.org/babylon/pull/4/files
 Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=4&range=00
  Stats: 36 lines in 1 file changed: 36 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/babylon/pull/4.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/4/head:pull/4

PR: https://git.openjdk.org/babylon/pull/4