make requires a file called Makefile in the same directory. That file is missing from the 4.6.2 release, or at least in the wrong place. I am reproducing a version of it here, which you can save as "Makefile".
# A very simple Makefile to generate the HTML docs
# Paths
XSLTPROC=/usr/bin/xsltproc
XSL=../../../acs-core-docs/www/xml/openacs.xsl
all: html
prelim:
cp -u *.png ..
html: prelim
cd .. ; $(XSLTPROC) $(XSL) xml/index.xml
To find out if you have DocBook and all the correct supporting libraries, look for xsltproc. DocBook, and this makefile in particular, have many dependencies, so if it's a remote machine you don't control, you should set your give-up threshold very low or you will waste a lot of time. In particular, xsltproc should be installed, openacs.xsl should point to a valid location for chunk.xsl (a template, part of an xsl stylesheet package, which we use as the foundation of our stylesheet), and the Makefile needs the right addresses for everything.