remove docs/reference.pdf, already included in manual.pdf
remove docs/reference.pdf, already included in manual.pdf

JackDanger/parenscript,JackDanger/parenscript,JDReutt/parenscript,manuel/parenscript,JackDanger/parenscript,vsedach/Parenscript,3b/parenscript,VincentToups/parenscript,fredericksilva/Parenscript