minor: moving introduction from the sidebar
DOCS-1790 Enterprise specific instructions with new yum and apt repos

Signed-off-by: Sam Kleinman <samk@10gen.com>
DOCS-1790 Add Ubuntu and rhel/centos Enterprise instructions to TOC

Signed-off-by: Sam Kleinman <samk@10gen.com>
DOCS-1790: edits for new enterprise tutorials
DOCS-1790: adding supporting redirects
DOCS-2771: move sharding access control
DOCS-2773: combine duplicated content about localhost
trivial: remove contents directive and fix list
DOCS-2600: minor tweak
DOCS-2692: removing bad redirect
DOCS-2692: note about behavior of split command
DOCS-2358 drop role behaviors