<i18n dev> RFR: 8261004: java.util.Formatter throws wrong exception for mismatched flags in %% conversion

[Ian Graves]

Updating the specification to reflect well-established behavior in Formatter when incorrect flags used for `%`.

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Commit messages:
 - Changing docs to reflect behavior

Changes: https://git.openjdk.java.net/jdk/pull/2389/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=2389&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8261004
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/2389.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/2389/head:pull/2389

PR: https://git.openjdk.java.net/jdk/pull/2389