<i18n dev> RFR: 8285370: Fix typo in jdk.charsets

[Magnus Ihse Bursie]

`codespell` could just find a single typo in the files covered by the i18n alias. Just fixing the typo did not make the comment more readable, so I rewrote it slightly.

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Commit messages:
 - Fix typo in charsets

Changes: https://git.openjdk.java.net/jdk/pull/8335/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=8335&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8285370
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8335.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8335/head:pull/8335

PR: https://git.openjdk.java.net/jdk/pull/8335