install docs: make more thorough
install docs: make more thorough

0x0mar/ngx_pagespeed,digideskio/ngx_pagespeed,wanrui/ngx_pagespeed,0x0mar/ngx_pagespeed,wanrui/ngx_pagespeed,digideskio/ngx_pagespeed,pagespeed/ngx_pagespeed,pagespeed/ngx_pagespeed