RFR: 8037384: Fix wording in Javadoc of java.io.Serializable

[Iris Clark]

On Thu, 19 Nov 2020 03:44:10 GMT, Stuart Marks <smarks at openjdk.org> wrote:

> 8231547: Serializable class doc should link to serialization specification
> 
> Rewrite a couple confusing sentences in the Serializable class doc. This does affect normative text, but the edits are primarily to focus and clarify the text, not to make any semantic changes. Thus, a CSR request shouldn't be required for this change.
> 
> Also add and adjust some links and link markup to the Java Object Serialization Specification.

Adjusted references look good.

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

Marked as reviewed by iris (Reviewer).

PR: https://git.openjdk.java.net/jdk/pull/1306