Refined Security Groups terminology article
Refined Security Groups terminology article

Improved the description; added more xrefs to the
community docs

Change-Id: I5fb8126f5bb07da58dd82973b5f2cdb71cd3238e

phillipsio/fuel-docs,stackforge/fuel-docs,stackforge/fuel-docs,phillipsio/fuel-docs,ogelbukh/fuel-docs,ogelbukh/fuel-docs,ogelbukh/fuel-docs,phillipsio/fuel-docs,ogelbukh/fuel-docs,phillipsio/fuel-docs