RFR: 8310987: Missing @since tag(s) in java/util/logging/ErrorManager.java

[Daniel Fuchs]

Please find here a trivial doc fix to add a missing `@since 1.4` to the java.util.logging.ErrorManager class.

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

Commit messages:
 - 8310987

Changes: https://git.openjdk.org/jdk/pull/14725/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14725&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8310987
  Stats: 2 lines in 1 file changed: 2 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/14725.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14725/head:pull/14725

PR: https://git.openjdk.org/jdk/pull/14725