Update free_skymaps.adoc
Update free_skymaps.adoc

Separated out angular maps browsing into own heading.
jMonkeyEngine/wiki.jmonkeyengine.org,jMonkeyEngine/wiki.jmonkeyengine.org,jMonkeyEngine/wiki.jmonkeyengine.org,jMonkeyEngine/wiki.jmonkeyengine.org