RFR: JDK-8318476: Add resource consumption note to BigInteger and BigDecimal [v5]

[Joe Darcy]

> Add informative notes to BigInteger and BigDecimal about possible running times, etc.

Joe Darcy has updated the pull request incrementally with two additional commits since the last revision:

 - Re-flow paragraph.
 - Fix a typo.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/16298/files
  - new: https://git.openjdk.org/jdk/pull/16298/files/0a48c48f..8968c924

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=16298&range=04
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=16298&range=03-04

  Stats: 6 lines in 1 file changed: 0 ins; 0 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/16298.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/16298/head:pull/16298

PR: https://git.openjdk.org/jdk/pull/16298