fix link to Java Image I/O guide

current Bio-Formats minimum requirement is Java 6
Merge pull request #801 from mtbc/java-imageio-link

fix link to Java Image I/O guide
Update auto-generated documentation

Repository: openmicroscopy/bioformats
Already up-to-date.

Generated by BIOFORMATS-docs-autogen-develop#119 (http://hudson.openmicroscopy.org.uk/job/BIOFORMATS-docs-autogen-develop/119/)