RFR: 8347008: beancontext package spec does not clearly explain why the API is deprecated

[Alexander Zvegintsev]

The beancontext package description or the deprecation text in the classes doesn't say anything about why the API is deprecated.
A few more words have been added in this regard.

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Commit messages:
 - 8347008: beancontext package spec does not clearly explain why the API is deprecated

Changes: https://git.openjdk.org/jdk/pull/23216/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=23216&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8347008
  Stats: 9 lines in 1 file changed: 3 ins; 0 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/23216.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23216/head:pull/23216

PR: https://git.openjdk.org/jdk/pull/23216