install gotchas

[simonmichael]

Hi @deech.. passing along some install feedback from a support session with a would-be haskell GUI programmer in #haskell today:

• they had given up attempting to install fltkhs because the stack command failed - they had 1.5.1 installed, which can't download things these days. README could mention how to check stack version and upgrade to the required (eg: stack upgrade).

• after they upgraded stack, I think they did not have ~/.local/bin in PATH, and weren't aware of that being a problem. Multiple stacks installed, running the wrong one etc. They requested some guidance on this in the README.

• they were on linux but the build failed after a while because they did not have autoconf installed. README could mention that it's required on all platforms, and how to check that it's installed.

• when we got to the demo itself.. we were happy, but after all that work I hoped for more of a reward. :-) Perhaps it should do something a little more flashy and impressive ?

I don't know how much detail you want to try and cover in your docs. https://hledger.org/download.html#check-your-path is what I say about PATH. In any case these were the gotchas today, I hope it's some help.

[PS we were following https://github.com/deech/fltkhs#readme / http://hackage.haskell.org/package/fltkhs#readme]