[elpa] externals/compat updated (edfc71a8b9 -> c4648b838f)

[ELPA Syncer]

elpasync pushed a change to branch externals/compat.

      from  edfc71a8b9 Remove unnecessary :max-version from require advice
       new  fbfbe3db89 Raise an error on duplicate compatibility definitions
       new  0c31f3a6e0 Mention new compat mailing lists
       new  c4648b838f Update GitHub comments in README


Summary of changes:
 README.md      | 20 ++++++++++++--------
 compat-macs.el |  2 ++
 2 files changed, 14 insertions(+), 8 deletions(-)