RFR: 8366105: Update link to the external RuleBasedBreakIterator documentation

[Volker Simonis]

The JavaDoc of `sun.text.RuleBasedBreakIterator` contains the following link to "Text Boundary Analysis in Java" by Richard Gillam which describes its implementation details:

http://www.ibm.com/java/education/boundaries/boundaries.html

This link isn't online anymore since at least 2001, but fortunately its original content can still be found trough archive.org at https://web.archive.org/web/20001117163900/http://www.ibm.com/java/education/boundaries/boundaries.html

Replace the naked link text with the title and author of the publication and the link target with a new link to the ICU project which is still available: https://icu-project.org/docs/papers/text_boundary_analysis_in_java/

-------------

Commit messages:
 - 8366105: Update link to the external RuleBasedBreakIterator documentation

Changes: https://git.openjdk.org/jdk/pull/26930/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26930&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8366105
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/26930.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26930/head:pull/26930

PR: https://git.openjdk.org/jdk/pull/26930