remove obsolete/broken link

Signed-off-by: Sam Kleinman <samk@10gen.com>
DOCS-1474 moved database-statistics to dbStats

Signed-off-by: Sam Kleinman <samk@10gen.com>
minor: cleaning up redundant pages from reference page
DOCS-1475: journal/nojournal clarification
minor: moving to standard field rather than key language.
DOCS-1481: initial draft of meta-query table
DOCS-1481: meta query operators using new reference section