Fix description for "Inapt spelling of 'MongoDB'"
Fix description for "Inapt spelling of 'MongoDB'"

There is an inapt spelling in the file called
ceilometer/doc/source/webapi/v2.rst.
  line194:...different meaning in Mongo DB and...
  line198:...the Mongo DB will return every....
  line199:See more in the Mongod DB doc.
I think "Mongo DB" and "Mongod DB" are supposed to
spelled as "MongoDB".

Change-Id: Icb72e5e5eb099a839c4ef5aba292a42976144428
Closes-Bug: #1488775

maestro-hybrid-cloud/ceilometer,eayunstack/ceilometer,isyippee/ceilometer,fabian4/ceilometer,ityaptin/ceilometer,cernops/ceilometer,fabian4/ceilometer,maestro-hybrid-cloud/ceilometer,idegtiarov/ceilometer,ityaptin/ceilometer,eayunstack/ceilometer,isyippee/ceilometer,idegtiarov/ceilometer,cernops/ceilometer,redhat-openstack/ceilometer,openstack/ceilometer,redhat-openstack/ceilometer,openstack/ceilometer