Document how KB is locally compiled

[compbioldev]

IMO that's a good idea, especially since a couple of issues (#117 or #118) might disrupt usual navigation, so this is a good alternative for those that cannot run and compile the KB locally (speaking of which, this is actually not documented on the README or contributing page). What do you think @Xiart @mahdi-robbani @konrad ?

Originally posted by @cpauvert in #96 (comment)