RFR: 8280366: (fs) Restore Files.createTempFile javadoc

[Brian Burkhalter]

This change reverts commit fb8fdc0fbf17dd7e900cb688df4917b97b26b9ab and then makes a smaller change to the verbiage of `Files.createTempFile `.

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Commit messages:
 - 8280366: (fs) Restore Files.createTempFile javadoc

Changes: https://git.openjdk.java.net/jdk/pull/7202/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7202&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8280366
  Stats: 7 lines in 1 file changed: 3 ins; 1 del; 3 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7202.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7202/head:pull/7202

PR: https://git.openjdk.java.net/jdk/pull/7202