RFR: 8371950: The jdk.httpclient.keepalive.timeout system networking property does not specify the behaviour for values <= 0 [v3]

[Daniel Fuchs]

> This change adds a sentence to the the description of the three keepalive properties to describe the effect of setting a value <= 0:
> 
>> If the provided value is negative, the default value is used. A value of 0 causes the timeout to fire immediately. 
> 
> I also took this opportunity to add a link from `module-info.java` to the `java.net.http` package description, and an `@see` link from the `java.net.http` package description to the `module-info`.
> 
> This is a doc change only - there is no code or behaviour change. Since it only affects jdk specific properties and is just a clarification of pre-existing behavior I believe no CSR is required. Please comment if you believe writing a CSR would be better.

Daniel Fuchs has updated the pull request incrementally with one additional commit since the last revision:

  More feedback

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Changes:
  - all: https://git.openjdk.org/jdk/pull/29587/files
  - new: https://git.openjdk.org/jdk/pull/29587/files/f326efc6..ed19a4de

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=29587&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=29587&range=01-02

  Stats: 7 lines in 1 file changed: 1 ins; 0 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/29587.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29587/head:pull/29587

PR: https://git.openjdk.org/jdk/pull/29587