message: Update build notes for dropping osx 10.7 support
  Github-Pull:
  Rebased-From:
diff: @@ -90,6 +90,6 @@ Uncheck everything except Qt Creator during the installation process.
  Notes
  -----
  -* Tested on OS X 10.7 through 10.11 on 64-bit Intel processors only.
  +* Tested on OS X 10.8 through 10.12 on 64-bit Intel processors only.
  * Building with downloaded Qt binaries is not officially supported. See the notes in [#7714](https://github.com/bitcoin/bitcoin/issues/7714)
  