RFR: JDK-8277303: Terminology mismatch between JLS17-3.9 and SE17's javax.lang.model.SourceVersion method specs

[Joe Darcy]

Please review this simple terminology update along with the corresponding CSR:

https://bugs.openjdk.java.net/browse/JDK-8277325

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Commit messages:
 - JDK-8277303: Terminology mismatch between JLS17-3.9 and SE17's javax.lang.model.SourceVersion method specs

Changes: https://git.openjdk.java.net/jdk/pull/6425/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=6425&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8277303
  Stats: 10 lines in 1 file changed: 0 ins; 0 del; 10 mod
  Patch: https://git.openjdk.java.net/jdk/pull/6425.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/6425/head:pull/6425

PR: https://git.openjdk.java.net/jdk/pull/6425