updated install/index.rst, fixed unused refs
updated install/index.rst, fixed unused refs

jbouyat/irma,hirokihamasaki/irma,hirokihamasaki/irma,quarkslab/irma,quarkslab/irma,jbouyat/irma,hirokihamasaki/irma,hirokihamasaki/irma,quarkslab/irma,quarkslab/irma,hirokihamasaki/irma,jbouyat/irma