added english text for safety.
вычитка idempotency
Дословный перевод куска с services—services #8
all changes in one commit.
Merge pull request #18 from nikolaifedorov/1-add-info-about-safety

add info about safety
Merge branch 'master' into gh-pages

* master:
  all changes in one commit.
  Дословный перевод куска с services—services #8
  вычитка idempotency
  added english text for safety.