RFR: 846: Document the need to enable Github Actions on personal forks that offer testing [v2]

[Robin Westberg]

> Forks created after pre-submit testing using GitHub actions was introduced need to explicitly allow GitHub actions. Post a notice as a separate check result if we detect this condition.

Robin Westberg has updated the pull request incrementally with one additional commit since the last revision:

  Better GitHub check

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Changes:
  - all: https://git.openjdk.java.net/skara/pull/974/files
  - new: https://git.openjdk.java.net/skara/pull/974/files/e9734bd2..191a7a8a

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=skara&pr=974&range=01
 - incr: https://webrevs.openjdk.java.net/?repo=skara&pr=974&range=00-01

  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/skara/pull/974.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/974/head:pull/974

PR: https://git.openjdk.java.net/skara/pull/974