RFR: 8309474: [IR Framework] Wrong @ForceCompile link in README

[Eric Nothum]

Fixed the @ForceCompile link to now actually point to the ForceCompile.java

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Commit messages:
 - 8309474: Fix ForceCompile link in README.md

Changes: https://git.openjdk.org/jdk/pull/14347/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14347&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8309474
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/14347.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14347/head:pull/14347

PR: https://git.openjdk.org/jdk/pull/14347