DOCS-1719 DOCS-1841 near operator

Signed-off-by: Sam Kleinman <samk@10gen.com>
DOCS-1719 and DOCS-1841: edits
DOCS-1589: Document the impact of having a hidden node being stopped and restarted regularly

Signed-off-by: Sam Kleinman <samk@10gen.com>
DOCS-1589: edits
DOCS-1842: Confusion in the Remove Shards from Cluster tutorial

Signed-off-by: Sam Kleinman <samk@10gen.com>
DOCS-1529: copyDB not supported in 2.4 with auth

Signed-off-by: Sam Kleinman <samk@10gen.com>
DOCS-1529: edits