[foreign-jextract] RFR: Update memory access and linker documents [v5]

[Maurizio Cimadamore]

> This patch updates the two documents describing usage of the foreign memory access and foreign linker API.

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

  Fix cross-doc hyperlink (was still pointing to cr.openjdk)

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Changes:
  - all: https://git.openjdk.java.net/panama-foreign/pull/475/files
  - new: https://git.openjdk.java.net/panama-foreign/pull/475/files/be46af2a..7c1378cc

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=panama-foreign&pr=475&range=04
 - incr: https://webrevs.openjdk.java.net/?repo=panama-foreign&pr=475&range=03-04

  Stats: 2 lines in 2 files changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.java.net/panama-foreign/pull/475.diff
  Fetch: git fetch https://git.openjdk.java.net/panama-foreign pull/475/head:pull/475

PR: https://git.openjdk.java.net/panama-foreign/pull/475