[oe] should indent recipe use "${prefix}" instead of "/usr"?

[Ross Burton]

>   just to be clear, this depends on where the indent software actually
> installs the documentation, yes? i'll have to check when i get home as
> to were that stuff is actually placed. for all i know, it *could* be
> under /usr/doc.

Yes.

That FILES suggests that the makefile is installing to /usr/doc/ and
needs to be told somehow to use $docdir.

Ross