Kitlog has worked for me. Yes, you can just check off and date your instructions (which I do also), but I use kitlog so family and friends can follow on the internet, and perhaps offer a few tips to other builders to share in this great community. I looked into webhosting, costs for domain names etc - kitlog was cheap as a one time payment of $50.
Someone mentioned expercraft - indeed free, but I did not like that it was hosted on a server - they crash or go away, so may your years of info. Kitlog is a program hosted on your own computer, and can be kept on multiple computers without additional charge, too. This allows me to keep a backup. Notes can written on a laptop in the shop, and the transfer of one file to the other computer will update that one. Two clicks, and the internet is updated.
So far, aside from aforementioned quirks, a happy customer... .