yum: added example for exclude parameter. (#26216)

* Added example for `exclude` parameter.

* Remove trailing whitespace

lib/ansible/modules/packaging/os/yum.py

@@ -194,6 +194,12 @@ EXAMPLES = '''
     name: '*'
     state: latest
 
+- name: upgrade all packages, excluding kernel & foo related packages
+  yum:
+    name: '*'
+    state: latest
+    exclude: kernel*,foo*
+
 - name: install 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