RFR: 8256679: Update serialization javadoc once JOSS changes for records are complete

[Julia Boes]

Now that the changes for record serialization are integrated into the Java Object Serialization Specification, this change updates the serialization javadocs in ObjectInputStream, ObjectOutputStream, Serializable and java.lang.Record. Additionally, the suppression of preview related warnings is removed in ObjectStreamClass.

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Commit messages:
 - fix link and new line
 - replace 'type' with 'class'
 - change javadoc wording and links
 - remove SuppressWarnings and change javadoc

Changes: https://git.openjdk.java.net/jdk/pull/1564/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1564&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8256679
  Stats: 58 lines in 5 files changed: 8 ins; 34 del; 16 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1564.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1564/head:pull/1564

PR: https://git.openjdk.java.net/jdk/pull/1564