added descriptions for yum options

Updated main description to state that the yum module will handle package groups.  Added descriptions for each example, as it is unclear to (some) users that @Name implies a group install.

library/packaging/yum

@@ -31,7 +31,7 @@ module: yum
 version_added: historical
 short_description: Manages packages with the I(yum) package manager
 description:
-     - Will install, upgrade, remove, and list packages with the I(yum) package manager.
+     - Will install, upgrade, remove, and list packages or package groups with the I(yum) package manager.
 options:
   name:
     description:
@@ -94,12 +94,19 @@ author: Seth Vidal
 '''
 
 EXAMPLES = '''
+# description: installs the latest version of httpd
 - yum: name=httpd state=latest
+# description: removes the httpd package
 - yum: name=httpd state=removed
+# description: installs the latest version of httpd from the testing repo
 - yum: name=httpd enablerepo=testing state=installed
+# description: upgrades all packages
 - yum: name=* state=latest
+# description: installs the nginx rpm from a remote repo
 - yum: name=http://nginx.org/packages/centos/6/noarch/RPMS/nginx-release-centos-6-0.el6.ngx.noarch.rpm state=present
+# description: installs nginx rpm from a local file
 - yum: name=/usr/local/src/nginx-release-centos-6-0.el6.ngx.noarch.rpm state=present
+# description: installs the package group 'Development tool'
 - yum: name="@Development tools" state=present
 '''