Revert "fix typo"

This reverts commit b1c88ebb30257aa94743aadda2fc6617f19b2cd1.
Revert "add SNMP reflection attack, this one is popular as well"

This reverts commit d26a0adbb0813bb1b750863ba56e45f93063ba1f.
Revert "update README.md"

This reverts commit ca5a6ceef4b4dd3c27393a5b9f8efabaf5f8bbaa.
add snmp attack and update README