Docs: Added new entry for the SIREn plugin.
Docs: Added new entry for the SIREn plugin.

Closes #6961

aparo/elasticsearch,fubuki/elasticsearch,fubuki/elasticsearch,aparo/elasticsearch,fubuki/elasticsearch,aparo/elasticsearch,fubuki/elasticsearch,aparo/elasticsearch,fubuki/elasticsearch,aparo/elasticsearch,fubuki/elasticsearch,aparo/elasticsearch