Merge branch 'Added_link_reset_root_password' into 'master'

Added link reset root password

Added text to link "How to reset root password"

cc/ @sytse

See merge request !1799

doc/security/README.md

@@ -4,3 +4,4 @@
 - [Rack attack](rack_attack.md)
 - [Web Hooks and insecure internal web services](webhooks.md)
 - [Information exclusivity](information_exclusivity.md)
+- [Reset your root password] (https://dev.gitlab.org/gitlab/gitlabhq/blob/How_to_Reset_your_root_password/doc/security/reset_root_password.md)
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