minor spelling correction :-)

Signed-off-by: Jeremy C. Andrus <jeremya@cs.columbia.edu>
Move iOS makefile to a more reasonable location

Signed-off-by: Jeremy C. Andrus <jeremya@cs.columbia.edu>
rename syscall_filter to api_filter

(it's more generic than just syscall filtering)

Signed-off-by: Jeremy C. Andrus <jeremya@cs.columbia.edu>
Updated documentation

Signed-off-by: Jeremy C. Andrus <jeremya@cs.columbia.edu>