[foreign-jextract] RFR: Refresh docs to reflect Java 18 API changes [v3]

[Maurizio Cimadamore]

> This patch updates the memory access and linker docs to reflect the Java 18 API changes.

Maurizio Cimadamore has updated the pull request incrementally with one additional commit since the last revision:

  Refresh jextract samples

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Changes:
  - all: https://git.openjdk.java.net/panama-foreign/pull/630/files
  - new: https://git.openjdk.java.net/panama-foreign/pull/630/files/94fdabc1..1ae15af3

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=panama-foreign&pr=630&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=panama-foreign&pr=630&range=01-02

  Stats: 91 lines in 1 file changed: 11 ins; 19 del; 61 mod
  Patch: https://git.openjdk.java.net/panama-foreign/pull/630.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-foreign pull/630/head:pull/630

PR: https://git.openjdk.java.net/panama-foreign/pull/630