update docs on numeric range queries
update docs on numeric range queries

ehealthafrica-ci/couchdb-lucene,eHealthAfrica/couchdb-lucene,ehealthafrica-ci/couchdb-lucene,rnewson/couchdb-lucene,rnewson/couchdb-lucene,rnewson/couchdb-lucene,eHealthAfrica/couchdb-lucene,ehealthafrica-ci/couchdb-lucene,eHealthAfrica/couchdb-lucene