RFR: Fixed bugs in bug filing instructions [v3]

[Jesper Wilhelmsson]

> Changed to the correct address for filing vulnerabilities and added some clarifications.

Jesper Wilhelmsson has updated the pull request incrementally with one additional commit since the last revision:

  Mooved text about priority

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Changes:
  - all: https://git.openjdk.java.net/guide/pull/57/files
  - new: https://git.openjdk.java.net/guide/pull/57/files/8ecb9a48..e7f8e90c

Webrevs:
 - full: https://webrevs.openjdk.java.net/?repo=guide&pr=57&range=02
 - incr: https://webrevs.openjdk.java.net/?repo=guide&pr=57&range=01-02

  Stats: 7 lines in 1 file changed: 2 ins; 2 del; 3 mod
  Patch: https://git.openjdk.java.net/guide/pull/57.diff
  Fetch: git fetch https://git.openjdk.java.net/guide pull/57/head:pull/57

PR: https://git.openjdk.java.net/guide/pull/57