Document OS install targets, NODE_PATH env var.
Document OS install targets, NODE_PATH env var.

maier/nad,HeinrichHartmann/nad,sean-/nad,sean-/nad,HeinrichHartmann/nad,esproul/nad,circonus-labs/nad,maier/nad,HeinrichHartmann/nad,esproul/nad,keithf4/nad,maier/nad,circonus-labs/nad,sean-/nad,keithf4/nad,hjhart/nad,maier/nad,esproul/nad,maier/nad,hjhart/nad,HeinrichHartmann/nad,HeinrichHartmann/nad,esproul/nad,keithf4/nad,sean-/nad,esproul/nad,maier/nad,hjhart/nad,circonus-labs/nad,circonus-labs/nad,hjhart/nad,HeinrichHartmann/nad,circonus-labs/nad,keithf4/nad,circonus-labs/nad,hjhart/nad,keithf4/nad,sean-/nad