Update maintenance status of Ruby 2.1

Since version 2.1.9, Ruby 2.1 is in the security maintenance phase.

Author: stomar

_config.yml

@@ -48,6 +48,7 @@ downloads:
         gz: 30c4b31697a4ca4ea0c8db8ad30cf45e6690a0f09687e5d483c933c03ca335e3
         xz: f86feaa0a578e8da0924ced3ec68b25b50d69fc9a72cc8d919bc3c73f85f87d7
         zip: d5094d7cc50266772a8352c68b7fcd865889fd174c09e2f11bb003696cd04bb3
+  security_maintenance:
     - version: 2.1.10
       url:
         bz2: https://cache.ruby-lang.org/pub/ruby/2.1/ruby-2.1.10.tar.bz2
@@ -59,7 +60,6 @@ downloads:
         gz: fb2e454d7a5e5a39eb54db0ec666f53eeb6edc593d1d2b970ae4d150b831dd20
         xz: 5be9f8d5d29d252cd7f969ab7550e31bbb001feb4a83532301c0dd3b5006e148
         zip: 21cf83156ec782d17827fb9c8a945626dfd68cf0d9eb5ca7a78b12eb91c6f1fb
-  security_maintenance:
   eol:
     - version: 2.0.0-p648
       url: