Update source/core/indexes.txt

Added index caveats wrt $or
initial cut of mongoperf doc
remove the general javascript variable arguments per scott's comment
DOCS-991: amending geospatial index requirement
merge: minor changes to forEach documentation
merge: DOCS-998
Repeated paragraph
Minor typo
upgrade correction
theme: fixing errant background
minor: fixing internal cross reference
minor: clarifying global lock information
Minor typo
minor: note about dropping text indexes
minor: removing documentation of non-existing command
DOCS-970 remove localhost from deploy rs doc
build: minor refactor
DOCS-996 modifying reference pages to be well formed
Minor typo
draft port of the smoke tests doc from the wiki.