PREFIX in README

[jwilk]

README reads:

You can overload the prefix path by defining the PREFIX environment variable before installing.

$ PREFIX=$HOME make install

However, with the advent of autotools-based build system, this no longer works.

[cemeyer]

DESTDIR= controls the root under which stuff is installed, at make install time — but if you configured with PREFIX of /usr/local, it'll just go to $DESTDIR/usr/local. Hm.

Maybe we should just specify that you should use the configure argument --prefix.