Typos and cleanup

Signed-off-by: Sam Kleinman <samk@10gen.com>
fixing compound index example
Fix incorrect spelling ($exist)

Signed-off-by: Sam Kleinman <samk@10gen.com>
DOCS-2026: removing link
DOCS-2011 add update operator examples with multiple fields
moving spec files around
DOCS-2011 moving syntax examples around
DOCS-2027: adding note to clarify
minor: syntax fix
DOCS-2017: balancing sharding tutorials in better categories
aggregation limit typo fix
admonition clarification
fix htaccess for security tutorial
DOCS-2031 whitespace changes
DOCS-2031: refactor structure of $nor page
DOCS-2031 fixing factual matter on $ nor issue
DOCS-1443 add more examples to all and in operators
Update capped-collections.txt

Typo in a phrase 'use cases' was 'uses cases'.

Signed-off-by: Sam Kleinman <samk@10gen.com>
DOCS-2034: refactoring organization of a page
DOCS-2034: adding cross reference