RFR: 8358634: RISC-V: Fix several broken documentation web-links

[Dingli Zhang]

Hi all,
Please take a look and review this PR, thanks!

Several RISC-V related documentation web-links are broken.
This PR updates the web-links.

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Commit messages:
 - 8358634: RISC-V: Fix several broken documentation web-links

Changes: https://git.openjdk.org/jdk/pull/25652/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25652&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8358634
  Stats: 4 lines in 2 files changed: 0 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/25652.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25652/head:pull/25652

PR: https://git.openjdk.org/jdk/pull/25652