Add installation instructions for windows users

[ShrykeWindgrace]

Add installation instructions for windows users who are facing the path too long issue on windows. Addresses #435

[alanz]

Thanks. Every bit helps

[nponeccop]

@alanz apparently it's not #435 but an unrelated issue. And now we have an instruction suggesting fairly terrible things to everyone on Windows. While in fact it's not for everyone but for those using " haskell-ide-engine somewhere deep in folder hierarchy" as @ShrykeWindgrace put it in #435.

The practice of creating anything out of home folder is as terrible on Windows as it is on Linux (although historically nobody cares - the tradition does back all the way to DOS and it's predecessors). "Normal" folders complying with Windows analog of Filesystem Hierarchy Standard such as c:\users\username\Documents\dev\foo\bar\quux\haskell-ide-engine work just fine, the path just cannot be too long. So the installation instruction should explicitly mention that it's a workaround for a rarely encountered issue.

[alanz]

Ok, so what to do?

[nponeccop]

the installation instruction should explicitly mention that it's a workaround for a rarely encountered issue.

Either I or @ShrykeWindgrace will change the instruction text when we have time. Hopefully tomorrow.

[ShrykeWindgrace]

On a second thought, I'd say it's better to revert the merge altogether. The workaround is windows-centric and has little to do with hie itself.