Merge pull request #9283 from fabi1cazenave/localizationNote-bug860530

bug 860530: add a “LOCALIZATION NOTE” to the email.en-US.properties file, r=stas(cherry picked from commit c9b550dae8a5ce6815466a94d1cbea89dab199fd)
Merge pull request #9285 from fabi1cazenave/bug860530-v1train

Merge pull request #9283 from fabi1cazenave/localizationNote-bug860530