[code-reflection] Integrated: Documenting SPIRV dependencies

[Gary Frost]

SPIRV backend has a dependency on TornadoVM and babylon/cr-examples/spirv project. 

These are now documented in hat/backends/spirv/README

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Commit messages:
 - Documenting SPIRV dependencies

Changes: https://git.openjdk.org/babylon/pull/132/files
  Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=132&range=00
  Stats: 131 lines in 2 files changed: 114 ins; 5 del; 12 mod
  Patch: https://git.openjdk.org/babylon/pull/132.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/132/head:pull/132

PR: https://git.openjdk.org/babylon/pull/132